confusion over distrobution/proportioning block

Air up front you mentioned. leaking calipers. But i cant see how. The seals are pretty tight in them. Especially if they are new.
Air would have to be pulled in through the dust boots as well.
residual valves are 2-3 psi on disc brakes and as much as 10 psi on drums.
disconnect battery and block pedal down,leave it there. The leak should show up.

One tell-tale, how many pedal cycles does it take to get air out?
For example if air is right away, its in caliper, if its several pumps then its master or combi valve.