Both.
There is bad English but not in terms of grammar or spelling (mostly.). Most sentences read like it's written by an ESL. It's kinda like getting a "please do the needful" email by the Indian tech dude in your company. It's technically correct, but whatever sentence they imagined in their native tongue does not translate well to English directly, i.e. actual native speakers find it really weird and would have used different words for the same thing. This sort of phrasing is very common in the game, where it's just a whole bunch of weird, unusual lines.
As for "idea", yeah, lines are bad. Characters don't have depth, they act like they're all neurotic and in general none of the romance or flirting is believable. Sure it's a fantasy world but people are people. They fall in love too fast, get angry too quickly, the lines are a mess.
Finding specific examples would probably help you a lot but I really can't be bothered to go back to the game and collect lines...sorry man. I appreciate the rest of the game and your efforts though.