Is there a way to remove the mod but change all the elemental spawners to normal? I tried removing it but acres and acres of spawners are gone.

Love the mod btw just want to see how my mega base runs without them atm

I figured it out for players who want to remove mod but not remove thick biter blanket that keeps them warm from all active chunks.

I downloaded another mod called "Delete empty chunks" removes all chunks without player entities
Saved game, deleted chunks button, as soon as it unfreezes hit escape (before radars vison comes back in) and save again under another file (Just in case)
Exited and removed mod. All chunks within one chunk from any building was redone with the normal biters when loaded the deleted chunk save with the no bobs enemys.

Game runs gorgeously now

Unfortunately there is no easy way to migrate on a mod's removal, only it's addition, and migration scripts run only once.
for something like what you request would need a mod removal .json migration file trigger to migrate all entities of a specific name to a different one of the same type.