I take it back.
I have a problem that's probably above my meagre skill level.
If I save a game with the new mod. It works fine.
I load the savegame. It works fine.
I load other savegames. That works fine.
I load back and forth between different savegames a few times:
The game takes a long time to load and runs through about About 5000 cycles of my mod according to my debug logs.
The world finally fades in with a long spam of text produced by my mod. Usually about how my feet are freezing. Which I assume is because the mod was running while the inventory hadn't been loaded yet.
Any grownups want to take a look at my code and tell me where I went wrong?
The intention is to save the two counters: "wetCount" and "attCount", so you do not remove wetness effects and attribute debuffs by loading. Everything else in the mod is re-checked each OnNewMagicRound so does not need to be saved.