Well I was trying to run OG with HD, the original game already had a French version (it's the one I've always played, even back in 2000). But I just learned that the HD mod was not directly compatible with it, though there might be workarounds. As is, it crashes as soon as I start a map.

Honestly even though I'd heard of the project before, I had competely forgotten about VCMI, so thank you for reminding me of it (very good timing too). If VCMI let me do what I am trying to do, really there's no point messing with the OG install. I'll try it when I can get back to it.