Various things I found around, which probably don't matter and will never see the light of day, and it's also a lot of interpretation and guessing and not confirmed in any way, but it's funny to think about these.

• “Hit [x] WONDERFULs” ACs are implemented. Will probably never be used though, because they would be literally impossible to clear in Autoplay. ¹⁾
• There are some values hinting at possible Live Multipliers (x2, x5 and x10). That was probably dropped in favour of Skip Tickets. ²⁾
• There is some stuff hinting at an implementation of “negative crits” which score 50% less Voltage instead of 50% more. Wouldn't that be an interesting song/note/AC gimmick? Crits are bad instead of good? Hmmm ³⁾
• The reason why you get 100 event points after every SBLSBL: Short for "SIFAS Big Live". A monthly co-op event where 20 players go for Group Goals and fight for MVP Titles.➔ Learn More live is that it was planned to make this value dependent on your individual Voltage rank (as in S/A/B/C/D, not the placement). It seems that this was dropped at some point, so now the database just sets the reward for every rank on every SBL song to a fixed 100. ⁴⁾
• It is possible for the game to show a video file instead of the 2D/3D MV in the background of a Live. This has not been used yet, though. ⁵⁾