Speaking as someone who knows absolutely nothing about the Japanese version, unless I was in a game that highly and regularly accepted AU characters, I think I would be incredibly put-off. This is in large part because I don't know what to expect from such a character and even though the stories go the same direction, as far as I know the characterization isn't entirely the same and the jokes are completely different (unless I'm mistaken, the majority of the jokes were americanized for the different audience).

Then again, I play in a game that does not accept AU character of any kinds. If I did, I might be a little more for it as long as I got a little warning what was going on first and what to expect. You might have better luck apping into a pre-established cast and checking with the cast mates first.

Also, I could be wrong but I do believe some players play "both". That is, they have enough knowledge and experience of both the english and japanese versions, yet still play using the English names (english location, etc). Honestly, that alone isn't too far of a stretch.