Except for some trailing spaces I have just found in my original proposed patches, I don't have any extra changes to add. So as soon as Brett answers about those two assignments, I would update and upload the patches diff file.

With regard to terminology, I believe 'Explicit is better than implicit' fits here.
IMHO using (in the code and docs) each of the three terms explicitly, with accordance to the glossary (https://docs.python.org/3/glossary.html#term-finder, https://docs.python.org/3/glossary.html#term-loader, https://docs.python.org/3/glossary.html#term-importer, all of which were first added back in revision 51025, BTW), makes the import mechanism clearer (than using 'importer' as an ambiguous term).