[0.75][bug] City Enchantments Do Not Update When Essence Increases

there are multiple issues with the way essence is currently coded when the quantity changes.  For example, if you build a scrying pool in a city with 2 essence, that now has 3, and then destroy the scrying pool...... You retain all 3 enchantments.   I wasn't aware the bug extends to calculations for the benefit of things like arcane forge though.   Hopefully that will help get more attention to the issue.

I can't confirm this. When I build a city with say 2 essence and cast a spell that gives 2 gold per essence I get 4 gold from that spell. I can see that in income details. When I build scrying pool and increase city essence to 3, on that turn that pool was built, it still says 4 gold. However, next turn it will show 6 gold and city income will increase correctly.

Same thing with meditation spell that gives 1 mana per essence. That one is easiest to test as you get it at the start of the game and new cities give 0 mana without it so any change in mana income from meditation spell is easy to spot. Try it and see if it works for you. Note that you need to wait one more turn after the pool is built to see the change.

I've noticed that hitting turn updates most such spells, including arcane forge.

You're right about ending the turn, but that only seems to work for Arcane Forge.  For Gentle Rain, it still doesn't update, and needs a recast.