My work today has been to look for game objects/prefabs that use the old font, and changed them to use the prescribed fonts. I think I’ve covered everything, except that the Build Report tool (yes I’m using this baby, really useful stuff) is saying that something is still using the old font.
The wisest thing to do then is to delete all the assets of that font (textures, materials, TK2D assets) and hope that the game will break due to a game object not finding the asset. Surprisingly, nothing breaks yet based on my playthrough and I just saved almost 1MB of game file size. But I hope to find the culprit(s) someday.