Actually I started studying Vietnamese several years ago but it was so difficult that I gave up at that time.

I was able to say "hello" and "I am Shiera" in English, Chinese and Korean immediately but it took three months to say them in Vietnamese.

As I posted here, I became able to make Vietnamese sentences a little as I post here, but I still caouldn't say the sentences.

I'd studied English in years, but I still I couldn't tell one after another of them.

Sometimes I was able to tell the words from the context and somewhat guessed what the story was.

I think focusing on listening to Vietnamese improved my hearing ability to hear English.

Now that the beautiful English ofn the CD is boring, I enjoy listening to people whose English has some kinds of accents on YoutTube.

After the cCorona problems are resolved, I believe I can enjoy conversations in English at Language exchange events.

Actually I started studying Vietnamese several years ago but it was so difficult, so I gave up at that time.

Yesterday, whilen I listeneding to English news for the first time in a while, I was able to catchunderstand the words.

I've becaome able to makwrite Vietnamese sentences a little as I post here, but I still can't say the sentences out loud.

Adding 'out loud' to the end emphasizes that it's the pronunciation that you struggle with. You can read the sentences in your head, but when you try to actually say them, only gibberish comes out.

Present perfect works better for the first part of the sentence. You still are able to write Vietnamese, so the event that happened in the past has a relationship with the present. Here's a link that can explain it better than me:
https://www.ecenglish.com/learnenglish/how-use-present-perfect

Yesterday, when Iile listeneding to English news for the first time in a while, I was able to catch the words.

"when" is used for events, "while" is used for activities that keeping going on in the background of other events or activities.

Some example sentences:
"When the English news came on [event], I decided to listen for the first time in a while. While listening [activity], I was able to catch some words"
"While driving to work [activity], I listened to the English news and was able to catch some of the words."
"When I caught some of the words in English [event], I was so excited!"
"While hearing and understanding all these words in English [activity], I kept getting more and more excited."

I'd studied English infor years, but I still I couldn't tell one after another of them.

Sometimes I was able to tellguess the words from the context and somewhat guessed what the story was.

Now that CD's beautiful English of CD is boring, I enjoyso I prefer listening to people whose English has some kinds of accents on Youtube.

Actually, I started studying Vietnamese several years ago but it was so difficult that I gave up at that time.

You need a comma after starting a sentence with an adverb like "actually". You also need "difficult THAT I gave up" so it sounds natural. Alternatively, you could use a semi-colon and/or a conjunction like "so". For example:" … but it was so difficult; so I gave up at that time"

Last year I started itlearning again.

You should specify what "it" is. You sentence would technically work, but it can be confusing when you don't reference anything specifically.

I was able to say "hello" and "I am Shiera" in English, Chinese and Korean immediately but it took three months to say them in Vietnamese.

Overall, this sentence is fairly decent. However, when you are talking about something said by someone or yourself, typically you will put quotations around what you are saying was said (a little tongue twister).

I became able to makwrite Vietnamese sentences a little as I post here, but I still can't saypeak the sentences.

Once again, you will want to be more specific with word choice so people understand what you are referencing, but overall this is fine.

I've been focusing on listening to the CDs everyday.

You may either want to specify what CDs (as in Language CDs) or simply generalise as CDs plural. It typically sounds odd to say "the" when referring to plural objects unless you are referencing something you specifically mentioned before.

As for English words, many Japanese people can't tell the difference between L and R; like Light and Right, S and Th like Sink and Think, V and B like Very and Berry.

You may want a semi-colon to try and avoid a run-on sentence and to make everything more cohesive.

I'dve studied English infor years, although I still I couldn't tell one after anofrom ther of themr.

I wasn't entirely sure what you were trying to say here, but you will want to change "I'd" since that is a contraction of "I had". It sounds quite awkward in English to say "I had studied English in years" as it sounds more like you are saying what measurement of time you use to say how long you studied English. To remedy this you would want to say "I've studied English for years" implying you still are learning; or, if you are no longer learning English you would say "I'd (or "I had") studied English for years". Keep in mind Contractions are informal, so don't use them on any formal pieces of writing like resumes or essays.

I haven't listened to English recently, though I wrote sentences.

Now that the beautiful English ofn the CD is boring, I enjoy listening to people whose English has some kinds of accents on Youtube.

Once again, I am not entirely certain what you meant to say by this, but usually you would refer to the content of something as being "on"; such as "on the USB" or "On the CD".

After the coronavirus problems are resolved, I believe I can enjoy conversations in English at Language exchange events.

You will probably want to be a little more specific with Coronavirus, since Corona is a type of beer as well. "corona" is slang at the moment and people would likely understand, but you will want to say Covid-19 or Coronavirus to be more specific.