Thank you, you are thoroughly awesome. I very much appreciate your help.
EDIT: It looks like I've taken it as far as it's willing to go for me. I can't find either the main game font or title screen font, so I'm guessing those actually
are compressed. And since I completely suck at this game and can't beat the sixth level, I can't check how the credits look, but I
suspect that they use the in-game font, since the Config font which I overwrote with English letters only included those characters which were necessary to the options screen, and nothing more. Here's a screenshot which encompasses everything I managed to change:
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I had to be a bit creative with the translations due to the eight character limit (though "backflip" is a more accurate description of the manoevre Astro performs anyway), and "catch" ultimately had to be dropped entirely (no great loss, as it's only used in one stage;
that damn stage six!), but for a first hack, I think it went decently, besides the fact that you guys ended up doing most of the work. :p I had fun, but I'll have to try messing with a simpler game next time.
While the likelihood of anyone being interested is precisely nil, the
IPS patch is available here. Apply it to a headerless ROM.
Thanks for all your help, guys.