Hi, lost access to my account when my old institution email was turned off, but after multiple emails to tech support and getting to Level 2, got my account transferred to my new institution email.
What worked for me, was starting the Canvas shell over from scratch, enabling new quizzes, then performing the import. Everything came in (almost) correctly. The issue with the names is not an import/export issue, I discovered.
This error is another sync issue between canvas and the new quiz engine which is external to canvas. Not yet sure about settings in general, but when you change quiz names, grades/re-grades, and even outcomes within canvas, they don't always sync with the new quiz engine. For example, if you update a quiz grade in the speedgrader quiz frame, it doesn't always update the grade in the grade/comment frame, nor in the gradebook. Sometimes the update happens immediately, sometimes after a few hours or not at all. I first noticed this during covid and have contacted tech support multiple times. It has gotten better but is still not completely fixed.
With regard to the names, some of my quizzes were created as test quizzes with generic names years ago. When I changed the names within canvas, everything showed up with the new name, so I didn't think about it again. When I finally got the import completed correctly, they imported with those old names rather than the new names, so this is part of those sync issues that need to be corrected.