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⁾
• The permanent Adv+ difficulties are not permanent - they will expire on the 18th July, 2025 at 15 JST. ⁶⁾
• There's drop rates for items in Training Camps in the database, but it seems they are not actually used, and the real drop rates are completely different. (Guess who spent several days investigating those database rates before giving up.) ⁷⁾