This sentence is from a book about Japanese grammar written for native Japanese speakers:
- The これ refers to a past incident where a Japanese teacher's explanation of the particle が to foreigners ended up being confusing and incomplete.
- Teramura-sensei is a Japanese teacher who the book refers to as a pioneer in Japanese language teaching.
"Incidentally, incidents like this are probably encountered by many Japanese teachers, and not just Teramura-sensei." seems like a reasonable translation, but I don't know what's going on with that ならずとも。 If it means "ならないとも" then I would expect to see a に or と just before (に・となる) but that doesn't seem to be the case.
Can anyone clarify what that ならずとも is signifying? Thanks in advance.