The Lovely High-Speed Train Workers

Nothing wrong with it, but adding "the" just makes it sound more like a title

I sat close to the bar counter this time when I went back to Shanghai byWhen I went back to Shanghai this time, I sat close to the bar counter in the high-speed train.

My original seat was not in that train car, but I was desperate to have a cup of coffee then and couldn't wait for the train attendant, so I went to the dining car.

By the way, you can have Starbucks' freshly ground coffee on high-speed trains in China.

After finishing my coffee, I decided to stay there because I had a big backpack, and it was a little bittoo crowded to return to my car.

But this time I noticed the other part ofside to these people.

As a train passenger, I could understand that policy, but I also understood the pity of this young woman that she couldn't discoverexplore southwest China with her best friends.

I thought it belonged to the passenger who was reading a book next to me.

As a result, I foundTurns out, it belonged to a serious police officer.

Luckily, her coworkers found thatrealized and called her back halfway.

I sat close to the [bar counter] this time when I went back to Shanghai by high-speed train.

“Bar counter” doesn’t sound idiomatic to me. “Bar” on its own would sound good, but then it would mean 酒吧, which probably wouldn’t be right in this context. I’ve never been on a train in China so I don’t know the layout of the dining cars, but I imagine the important point is that you sat near the place where the attendants were doing their work, which enabled you to hear what they were chatting about. This phrasing might work:

“During this return trip to Shanghai by high-speed train, I sat near the counter in the dining car.”

(I added “in the dining car” because “counter” on its own would be ambiguous.)

By the way, you can have Starbucks freshly ground Starbucks coffee on high-speed trains in China.

After finishing my coffee, I decided to stay there because I had a big backpack, and it was a little bit too crowded to return to my car.

But this time I noticed the another partside of these people.

The girl scheduling meals was feeling sorry that she couldn't have a vacation with her coworkers because company policy says they can't all take time off at the same time.

The other correctors suggestions (regret, etc.) are valid here, but I think “sorry” is also fine, depending on her actual mood and emotions.

I thought it belonged to the passenger reading a book next to me, but it turned out to belong to a serious police officer.

He iwas a very nice young man and gave me some great advice on train travelling.

Luckily, her coworkers founnoticed/discovered that and called her back halfway.

I think they are a group of lovely(or: were) {lovely people | a lovely group of people}.

“I think they're lovely people” is fine, but if we add “a group of” then we move “lovely” before group. I think we do this because “think” can be ambiguous: it sometimes means “I believe this,” but other times it means “I’m uncertain about this.”
“I think they’re a group” could mean “I’m not certain they’re a group,” but “I think they’re a lovely group” clearly means “I believe they’re lovely.”

I hope my explanation makes sense, but if not, please feel free to ask me. :-)

I sat close to the bar counter this time when I went back to Shanghai by high-speed train.

高铁有吧嘛？才知道了

My original seat was not in that train car, but I was desperate to have a cup of coffee right then and couldn't wait for the train attendant, so I went to the dining car.

By the way, you can have Starbucks freshly ground Starbucks coffee on high-speed trains in China.

After finishing my coffee, I decided to stay there because I had a big backpack, and it was a little bit too crowded to return to my car.

But this time I noticed the another part ofside to these people.

The girl scheduling meals was feeling sorryregretting that she couldn't have a vacation with her coworkers because company policy says they can't all take time off at the same time.

As a train passenger, I could understand that policy, but I also understood the pityfrustration of this young woman that she couldn't discoverexplore southwest China with her best friends.

As a result, I foundTurns out it belonged to a serious-looking police officer.

He liked to grab a sip every time he walked by.

这危险啊，don't leave your drinks unattended

Sometimes they were quite busy, and one of them even took the wrong meal by mistake.

I think "even" doesn't fit here. You could say one of them took the wrong meal amidst the confusion or something.

Luckily, her coworkers founrealized that and called her back halfway.

I think "luckily" is a bit 夸张 here but I can't think of a better word. Luckily makes it sound like something bad would have happened, but in this case, she'd just have to walk back and take the right meal.

I think they are a lovely group of lovely people.

Next time, if a train worker gives me the wrong snack or something, I will not be angry or unhappycomplain.

My original seat was not in that train car, but I was desperate to have a cup of coffee then and couldn't wait for the train attendant, so I went to the dining car.

The "then" sounds off in this sentence. It isn't needed because we understand perfectly what you mean. If you want to insist on when this happened, it would be better to say "I was desperate for a cup of coffee at that time and..."

After finishing my coffee, I decided to stay there because I had a big backpack, and it was a little bit too crowded to return to my car.

But this time I noticed the other partperspective/point of view of these people.

The girl scheduling meals was feeling sorrybad/disappointed that she couldn't have a vacation with her coworkers because company policy says they can't all take time off at the same time.

As a train passenger, I could understand that policy, but I also understood the pitydisappointment of this young woman that she couldn't discovertravel to southwest China with her best friends.

He liked to grabtake a sip every time he walked by.

He iwas a very nice young man and gave me some great advice on train travelling.

Even if he probably still IS a nice man, you should keep all your verbs in past tense for clarity.

Luckily, her coworkers founrealised that and called her back halfway.

I sat close to the bar counter this time when I went back to Shanghai by high-speed train.

If you say "near the bar", it is already clear from context that you mean near the counter at the bar :) Including the word "counter" then only adds confusion.

After finishing my coffee, I decided to stay there because I had a big backpack, and it was a little bittoo crowded to return to my car.

But this time I noticed the saw another partside of these people.

"to see another side of [someone]" is the typical phrase

The girl scheduling meals was feeling sorrybad that she couldn't have a vacation with her coworkers because company policy says they can't all take time off at the same time.

"Feeling sorry" means you feel bad about something bad that you did.
"Feeling sorry for [someone]" would typically imply that you feel sad about something bad that happened to someone else.
"Feeling sorry for [herself/himself/myself...]" tends to be quite negative, meaning we think someone is pitying themselves when they shouldn't be.
So in this case, I think it fits your message best to say she's feeling bad instead of feeling sorry.

As a train passenger, I could understand that policy, but I also understood the pitydisappointment of this young woman that she couldn't discover southwest China with her best friends.

Pity is similar to feeling sorry (see above). You can pity others, but it's quite negative to say that someone pities themself, so that doesn't quite fit your message of viewing this woman positively.

As a resultHowever, I found it belonged to a serious police officer.

"As a result" would need to be showing the result of some action that caused it. Here, we do not learn how you found out it belonged to the police officer, so the phrase "as a result" doesn't work here.

Luckily, her coworkers found thatnoticed and called her back when she was only halfway gone.

I think they are a lovely group of lovely people.

"A group of lovely people" is perfectly understandable and grammatical, but the typical phrase is "a lovely group/bunch of people".