Fully agree about a tutorial, as much as I hate them it probably needed one. Part of the problem was the original design only had the beats, it wasn't until 2 days in I realised how painful and silly it was to have to manually hardcode the charger position/timing separately for every level to make sure they were hittable mid-charge (while also being extremely tricky to line up the shots) so I added the whole timeline scrubbing system.
Then I had the issue of two similar, but mechanically separate, concepts and no existing plan to distinguish them to the player, plus a lot of time spent adding a fairly complicated system to my "basic input mechanic" plan lol. I just didn't have time to properly rethink the onboarding/HUD to make it nice and clear.