Tomorrow is ourthe Spring Lantern Festival in China.

We tTraditionally we have lanterns, sticky rice dumplings, and fireworks on this special day.

If I amwere still in my hometown, we'll would celebrate it in our house with family, but I'm in Shanghai right now.

Luckily, there are several lantern shows in this cityhere.

I'm going to visit one of them.

Alternative:
I plan to visit one of them.

It's in a small town, a lbittle far from downtown Shanghai.

"a little far" sounds unnatural to me. I changed it to "a bit far"

In this caseThat way, I will spend four hours goetting there and back tomorrow.

It wouldill be tiring, but I believe it will be worth it.

Time should be wastedShouldn't time be spent on beautiful things.?

Your original text in Chinese posed a question here.

time wasted on beautiful things: this doesn't make sense, so I changed it to "time spent on beautiful things"

If I amwas still in my hometown, we'll would celebrate it in our house with family, but I'm in Shanghai right now.

Two very small corrections, please don't be disheartened by the large amount of text below.
"If I am still in my hometown" seems to imply that you are currently in your hometown and there's a possibility that you could still be in your hometown during the lantern festivals, but there's also a chance you might have left by that time. Since you are already no longer in your hometown, I feel changing it to "If I was" because that implies that you are talking about the past when you used to live in your hometown. So it's saying, you used to live in your hometown, but you no longer do.
"we'll celebrate it" would fit with "If I am still in my hometown" meaning you still live in your hometown and if you haven't moved by then, this is what you would do "we'll celebrate it." However, since you no longer live in your hometown changing "we'll" to "we would" (or "we'd" to keep using a contraction) implies that this is what happened in the past, but isn't going to happen in the future since you no longer live in your hometown.

Luckily, there are several lantern showfestivals in this city.

Note: This might be a correction that only makes sense in the Northeast United States
Festival can be used to imply a certain timeframe (possibly days) where a holiday celebration takes place. Festival can also be used for a location and time when a celebration of that specific festival takes place. Yes, it's confusing. There can be many festivals (outdoor/public celebrations for a specific festival) happening for a single festival.
An example might be "Fall Festivals", those can take place in many places, at many different times, with a variety of different activities, but they are all celebrating the single event of the start of Fall.
However, there are some celebrations, like in the United States the Fourth of July, where we'll call them celebrations instead of festivals, and if we're talking about the Fireworks in particular we call them "Firework shows" not firework celebrations or firework festivals. It's really arbitrary and if I knew how we decided what word to use when I'd tell you, but I don't know other than exposure. It's also possible it varies regionally. If I had to make an educated guess, I would say a festival or celebration includes more interaction on the attendees part, meanwhile a "show" there aren't really activities, you go to watch something like a movie or someone else light up a bunch of fireworks. In those cases there aren't any structured activities. Whereas festivals usually involve crafts and celebrations usually involve food.

In this case, I will spendit's four hours going there and back tomorrow.

A more concise way of saying this would be "it's going to be a four hour roundtrip" or "it's going to take four hours getting there and back" the reason I'm using "getting there and back" instead of "going there and back" is because when you use "getting" it emphasizes that the action is completed. So once you finish getting to your destination and returning from your destination it will be four hours. By using "getting there and back" you are implying that this is travel time only, and not talking about any time you actually spend at your destination.
I hope that makes sense, I had to look up the difference between getting and going myself. I know what "sounds right" but don't always understand why.

While you are spending time traveling there and back, if a person is "spending" something it usually isn't about the time, it's more about an action, like "I am spending money to travel to this event" or "I am spending time with friends" I suppose you could say "I will spend four hours traveling there and back tomorrow". "Going" doesn't work here because it's too vague. If you're simply talking about how many hours it will take to do something we use the word "take". "It will take X hours to do Y" Since the idea here is that you are going to be sitting on a train or bus to your destination you aren't really doing anything during that time other than waiting for something to happen "the bus or train to reach your destination." In that case you talk more about the time being taken away from you since that's really all that's happening. You wouldn't say "I'm spending time waiting for my friend" you would say "I'm waiting for my frend" because that's the action that's happening, you are actively waiting for something. I have no idea if I explained that correctly.

It wouldill be tiring, but I believe it will be worth it.

"will" implies this is going to happen in the future.
One could argue that "would" works if you were talking hypothetically, as in, you aren't actually going to do something, but you are creating a scenario where if you were in a situation to do that "In that case, it would be tiring, but I believe it would be worth it." However, since this is something you plan on actually doing in the future, we use "will" instead of "would."

Time should be wasted on beautiful things.

This is very poetic, if you mean for it to be poetic then it's perfect.
Wasted has a negative connotation, which is why it makes this sentence more poetic, because "beautiful things" are a positive thing, everyone loves beautiful things (we all interpret what is beautiful in our own way, it doesn't mean it has to be visual. Acts of charity of a scientific discovery could be seen as beautiful things) By contracting a negative term "wasted" with something positive "beautiful things" it creates this contrast. That is why I say how you phrased it is poetic.

If you mean to be less poetic, I would change it to be "Time should be spent on beautiful things." That is a more direct way of saying it. Which can be helpful when people with people who might see poetry as being "dramatic".

Tomorrow is ourthe Spring Lantern Festival in China.

We tTraditionally, we have lanterns, sticky rice dumplings, and fireworks on this special day.

"As is tradition" type of phrases are usually introduce before the subject verb object bits. Traditionally have is something that is said but is less natural in context.

IfWhen I am still in my hometown, we'll celebrate it in our house with family, but I'm in Shanghai right now.

If makes it sound like you don't know but you do.

I'm going to visit one of them.

I'm planning to visit one.

would sound more natural to me but what you wrote is not wrong and if you like it better it's fine.

It's in a small town, a little far from downtown Shanghai.

so "a little far" is a great descriptor in general because it's almost contrary to itself but I think I would reword it to something slightly different like
"and a little far from"
or
", far from"

leaving out the word "little".

In this caseAs such, I will spend four hours going there and back tomorrow.

you didn't introduce a case so you need a different conjunction

It wouldill be tiring, but I believe it will be worth it.

small mistake to make one time but if you find you make this many times it may be worth investigating

Time should be wasted on beautiful things.

This is not wrong but there are more natural ways to express this ideas that are sort of classics in English.

"Time is never wasted on beautiful things" is a negatively word positive sentiment that many people would find more compelling here for example.

Happy Spring Lantern Festival.!

Happy X! type statements feel like a threat without the exclamation mark.

If I amwere still in my hometown, we'll would celebrate it in our house with family, but I'm in Shanghai right now.

Luckily, there are several lantern shows in this cityhere.

Original sentence is grammatically correct. My correction is to make it sound more natural.

It wouldill be tiring, but I believe it will be worth it.