you might have missed some as there are 51 files that were changed.Eternum Music Restoration Mod
TL;DR of what's below: Download mod > grab game folder > put in eternum folder. Unless you've unpacked the RPA you won't have to overwrite anything
Ok it seems that the game prioritizes /game/audio/music over the .rpa version, so all that needs to be done is unpack the zip, grab the game folder and drag it into your Eternum folder. That should restore the music back to the original songs. I've tested it on a few songs in a freshly unpacked 0.8.6 version (windows, specifically) and it played the original music.
Unless Caribdis has to remove more songs again in the future, this should be futureproof and safe to use in all versions from 0.8.6 and above to restore the music that was used in 0.8.5 and before
and luna's scene in 0.7 has two files "pilgrim1" and "pilgrim2" that were changed into a single track "lunasex1".