I dunno about grammar, but I've heard when some older games had their English audio done by a Japanese director (guess it goes for some anime too?), they were told to speak more slowly/clearly/loudly for a Japanese audience to understand what they were saying, at the expense of sounding cheesy to us.
I think it's just the publisher not wanting to pay or like you said take time out for proper translation. Though if I made a game, I might put bad grammar in intentionally as a nostalgic joke.


