via the expedient of adding an on_added() method to the golem when it's created to check and re-sync with the player's level every time it's re-added to the map.(Now, other users have reported the same thing happening with other sidekicks like Writhing Ones' worm that walks or Annihilators' mecharachnid. I haven't seen this happen, and after staring at the code for a while, I'm convinced that the existing code should prevent that from happening, but just in case, we also add similar on_added() handling to those sidekicks.)
And since this is a bugfix addon, it's probably not suitable for inclusion in ZOmnibus, since it would have to be clawed back out if/when the bug was eventually fixed.