Using /track villager iron_golem_spawning or /track villager breeding deletes custom names given to villagers when /track villager clear is used.

This is a known bug.....

Thanks for the info... I did a search on previous bug reports and didn't find it.

The /track command is a bit legacy, all of it's functionality has been moved to the ai_tracker app (/script load ai_tracker), that doesn't modify the entity names. I believe the only reason /track is still around is because you need carpet in your client to be able to see the texts in the app version.