I eventually caved in and tried resetting my phone. When the first-time-setup came up, I selected "English (Canada)" as the language (it had defaulted to "English (United States)"). It offered to restore from a backup I had made just prior, and all my
apps started downloading. When "Preview for Developers" was ready, I re-enrolled, and searched for the update before making any other changes to the phone's Settings. This time it downloaded and installed without any problems.
When it was done, I removed the French keyboard and made some other tweaks, but everything seems to be working, even Cortana (although she doesn't seem to want to tell me a joke or anything like the US version did...).
The only issue I'm having now is that the Store keeps trying to update 3 apps (Podcasts, Calendar, and Battery Saver), but can't. I keep getting the error code: 81030137 on each.
Not sure if it's important, but before I did the reset, I made a backup, but it wouldn't work initially. I had to *delete* my existing backup before it would successfully make a new backup. NB: The restore worked well, keeping my Start screen layout and
reinstalling apps, but there needs to be some more work done - individual app's save states were not restored (eg. Twitter accounts, game progress, etc.). This is disappointing as compared to Apple's efforts.
Anyway - thought I'd give an update to the team. Thanks. Love the Folder implementation and adjustments to IE. :)