Yes , that is a good sign.. in the sense that the problem is usually the actuator at the end of that vac line is ruptured ..but if it holds vac , it isn't.

The valves you mention are simply engine source vac check valves.

To check all funtions , one has to put a tee in-line and monitor a vac gauge through the windshield to verify ECU sig to SOV when car is cold, but there is a simple trick one can use to check the system working from the actuator back..
If you take the engine vac feed line to SOV, disconnect it at SOV, start engine and see if you have vac at this line [ this is a simple finger over hose end test] If yes, then couple that feed line to the line going to trans [grn one] , this test will have eliminated both the sov and the ECU from the system.. now, just take the car down the road and see if one has delay shift.. if NO, you have an actuator/cable problem..if yes, actuator/cable and line from SOV are verified working/good. You possibly have no vac feed to grn hose due to : broken line /sov stuck, or no ECU sig to operate sol on SOV. This will entail a voltage checks, etc.., but the first diagnosis should be actuator verification..