User blog comment:RottenBlock/Toushin Toshi 1 Patch 1.5/@comment-31720212-20200415225101/@comment-31720212-20200423003708

I do have a pretty good understanding of the program, actually. inmm works by first patching the EXE and then re-routing all calls to play CD music to play through inmm instead. The ini file is used to tell inmm which file to use to replace each CD track.

My best guess for why it would be causing trouble in games that don't use CD music is that the EXEs used in those games might have been borrowed, patched inmm EXEs by mistake. Since the games we're talking about don't play CD music, they don't have any reason to contact inmm, so I'm still confused as to why they'd be throwing errors, but it's possible that the issues are caused by inmm's absence all the same. If you want, you could try using the original Japanese 3.5 EXE, but at this point that would be splitting hairs, since the error seems to be solved!