...I think you're majorly overthinking/overstating the whole thing. To me it doesn't seem like all that much has actually changed and/or is to be changed compared to the existing v0.9.1.
The following literally is the or the planned-to-be entire music change log since v0.9.1, and I've even been very all-encompassing by including things that aren't directly related to the actual .ogg music files
- include that elusive "RN vs Classic" music switch that you've supposedly been working on
- replace all "_vita.ogg" songs and their according "ogg.sli" files with their iOS/Android rip except for bgm01_vita and bgm52_vita
- replace bgm01_vita.ogg, bgm52_vita.ogg, and bgm52.ogg with each song's according "NM64 mix" (.ogg.sli is already identical for bgm01_vita and the other two didn't have .ogg.sli)
- include looping for bgm52.ogg and bgm52_vita
- enable looping for bgm52/bgm52_vita when "disable forced auto-read" is checked
- when "disable forced auto-read" is checked, have the music to fade out in last episode's "epilogue" before Saber says "welcome back, Shirou"
- fix the bug/feature where the music does not play when loading a save that was created in the middle last episode's "epilogue"
- replace bgm49.ogg and bgm51.ogg (along with both song's according sli files) with iOS/Android rip
- include bgm77.ogg + bgm77.ogg.sli info from the iOS/Android rip for only the final final battle of HF
- include some sort of toggle for bgm77 so that people can choose to disable it while still having the RN-exclusive music
- expose bgm43trial, demo01_ps2, demo04_ps2, and ステータス_ps2 in the GUI in some manner (demo02_ps2 and demo03_ps2 are not musically different enough for use outside of the trial's "demo" not-so-movie)
- remove and delete bgm52_ps2, bgm55_ps2, bgm68_ps2, bgm70_ps2, and bgm76_ps2 - both their .ogg and .ogg.sli files
I also personally was vouching for some changes to the credits music, like having bgm27 play for the HF true end, and maybe having bgm68_classic play for specifically the Fate end or maybe instead for the UBW good end, but all of this was not something that was agreed upon and was just kind of me vocally thinking out loud.