Finally got a copy of Brilliance after all these years! The installer asks to copy an included program, SetPatchMrgCop, to C: and to run it in user-startup. It says it's a patch for bugs present in all versions of the OS.
Does anyone have a better idea of what it does and whether it's still necessary with OS 3.1 and SetPatch v43 (which were not available at the time Brilliance shipped)?
A quick hex read of the file shows that it's doing something with a .resource and graphics.library. If anyone has more experience with this tool please chime in

Would prefer not to have random patches running on my system - trying to keep this machine as a very clean 3.1 setup. I'll probably remove it from user-startup and run it at go-time for Brilliance.