Jobb,
You are quite skilled with your English transations.
As I read it, nothing jumped out at me as being incorrect.
Some small items.
1) Comma usage
If we look at
item 13, we note the following sentence is incorrect.
I turned the corner, and ran smack into a patrol car.
Do you think your following sentence is similar?
"Afterward, Liu Bei agreed to help Cao Cao attack another warlord, and set off from Xuchang with his troops."
If you think there might be a problem, I would look at your work closely to see if there are other examples.
e.g. "Cao Cao dismissed Liu Bei as a coward, and paid no more attention to him."??
2) "Once Guan Yu and Zhang Fei asked him, "Why don't you care about the country but only grow vegetables?"
This seems a bit odd to me. I can't see the original, and even if I did, I would not understand it. But here are some thoughts....
a) If you care about OUR country, why are you busy wasting time growing vegetables?
3) "Unnerved, Liu Bei dropped his chopsticks on the floor." If he was unnerved, then why did he drop his chopsticks and why was he afraid of the thunder. He doesn't sound so unnerved to me.
I think you've done extremely well. I hope my comments are of benefit.