Personal ending, not necessarily.I recommend getting a native English speaker who is fluent with Chinese in order to make conversation smooth. I don't mind cultural differences but delivering the message from one language to another is not easy, especially considering all the differences between English and Mandarin Chinese.
I also recommend dev to finnish the main game first before branching the plot into different endings, I think the elf ending would satisfy most of players. The problem of dividing the plot in the middle of the game is that the workload easily doubles, triples, and most of the players won't notice the effort for they follow a special ending. Ravager is a perfect example of this mistake: instead of finnishing the main plot the devs decided to follow the plotline of each girl, and now more after a year the main plot has not developed at all. It is much more difficult to finish the game with +10 different endings than one, but it is much more easier to expand the existing game towards the direction the players want.
There may be a different ending in the end, but not necessarily a personal ending.
Regarding the English question, my current English translator is a very responsible translator and he is very good.
This aspect I think is mainly because I am not a good writer, which causes him a lot of difficulties in translation. I apologize for that.