Does Numbers 12 really not support user-created custom templates?

In hindsight I realize it sounds stupid, but what seems to have happened is that the app, virgin to the new MacBookPro, never got the large cohort of my custom templates transferred when I did migration assistant. Since there were no templates CREATED in the new version of the app, there was no category for custom templates. If it is how the transition works, though it's crap, because I had to get out the old computer, transfer the templates one by one to a folder, load the folder into the new Numbers, open each one separately, and save it as a new template. Once just one of those had gone through that process, which took the better part of an hour, then at least the command 'save as template' became visible. But surely all the user templates should have been loaded during the migration?

Yes, I finally figured out that when I moved all my stuff from the failing butterly-keyboard MacBookPro to the new machine, Migration Assistant managed to fail to move all of my many already-made custom templates. I was able to open them on the old machine, and take each blank template after opening it and move it to a folder, then manually RE-save them as custom templates in the new Numbers application.

Although no one proposed this as my problem, reading the various replies I have gotten helped me to get some clarify in my mind about how to proceed, and for that I'm very grateful.