Please focus on the return-side plumbing that follows the left valve actuator.
Pipes from left to right:
2" - spa jets
2" - paramount six-port water valves (two) (both get pressure even when all the return side valves after the actuator valve are closed)
1" - ? (open and close 0.5 PSI bounce 0.5 PSI change)
1.5" - ? (open and close 4 PSI bounce 0.5 PSI change)
2" - spa spillway
There's an IDC (in-deck debris canister) but it's non-venturi (not return-side powered).
There are wall returns but they are plumbed to one or both of the paramount six-port water valves (they intermittently have flow).