Amazing, after a factory data reset ( under system setting menu ), the auto-rotation seems fine with camera app. No crash and laggy anymore.
Here is my guess of what happened, I think maybe the "flash with data format" doesn't work what it should be, and if you already used 13U with CN rom for a while like me and flash EU with clean install, there is something not cleared totally and make system buggy like auto-rotation not working and restart abnormally.But if you are factory reset your 13U before/after flashing EU rom, then you may be fined with it and no big issues.
Anyway, I will keep using it as a main phone and take it to my trip because of it's great camera, hope everything is fine.
Thank you again and it really save me a day.