Need some vault advice

You upgraded your last spymaster to level 3. This is where you f’d up. You used the upgrade medallion. Spymasters evolve from level 1 to 2 by killing another spymaster that can be destabilised. When you have at least one lv1 spymaster the game is very likely to give you another one so you can upgrade from level 1 to level 2. All your spymasters being level 3 the game is very unlikely to give you another. Just run temples, pray and hope. From now on when you eventually get another spymaster (that can be very long in your situation, from given rooms or utilities medallions dropped by some rooms) put it at the end of your chain lock it and don’t upgrade it with the upgrade medallion until you get another lvl 1 spymaster. Once you get another spymaster, they should drop more frequently. I was in the same situation and I fixed it by putting as much guardhouses as possible. The game gives rooms that can link to rooms you already have. Guardhouses can only link to 3 room types out of the 14 that exist. Spymaster is one of those 3. Put all the guardhouses you can on your junk/bait chain. Hope to get spymaster. Don’t upgrade it, and lock it. Good luck dude.

Why are you calling the temple “vault”?