It's possible that accent marks are built into the font already, I'd have to double check that. The main issue is that different bits of dialogue are scattered across several different objects and are baked into the code instead of being drawn from a separate file. Right now the only way to make a translation would be to crack the game open and manually replace all those lines, but you'd have to know where to look as well since they're in different places. I've been trying to sort through things so you can go through a single text file to make a translation without having to wade through my poor code structure. Partially for my sake as well since even I have trouble remembering where some of the smaller more unique snippets of dialogue are kept at this point!
That would be very good, I tried to make a Spanish translation like that, having to look for where each dialogue was XD
About the accent marks, the font of the initial menu did have them but the one used for the dialogues within the game did not, because in several cases it only showed a square when they had to show some letters such as á for example.
Also, It's good to know that then I won't have to complicate myself so much anymore and I'll just have to wait for it to be possible to do a translation with the method you plan to implement, it sounds much more comfortable UwU