But anyways, do we align the left side to player 1's stick, or the carriage bolts?
I've been pondering this lately. Perhaps to put this another way, I think that you should group the buttons and stick into one 'item'. Then position the group as you see fit such as left edge of CP to left edge of left group same distance as right edge of CP to right edge of right group.
The $64,000 question is (as you realize): is the left edge of the left group the stick or the CP bolts? Or is it some other 'amount' (say to the edge of the dustwasher). Perhaps a good method to determine this is to add 'Knievel' button halos to the group, then you can position the groups to the edges of the halos.
Of course, there is no right or wrong way. I, like you, am wanting it to look balanced, evenly spaced, and aesthetically pleasing.
Not really an answer, but perhaps food for thought...
Rick