Thanks for your feedback and responses everyone! I haven't been able to find any tools for Sinsemilla, but it seems Applique's DRM removing patch may have also removed encryption (?). I tried out a few tools here and there like KrkrExtract and GARbro, as well as KiriKiri Tools, but XP3Viewer miraculously worked! I now have all scripts in plaintext, along with other resources for the game!
You certainly have a point, Infernoplex, but even so I'd like to try my hand at it. From what I've played so far, the language is not as hard and nuanced as Hatsuyuki Sakura, plus even if I fail, there are have been no active translation projects over the nine years since its release, so I don't think anyone will mind. It'll certainly be a fun learning experience, and a way to give back to the community if I do succeed (one day)!