In my experience e10s in Firefox before 57 was quirky.
Interesting. I didn't need to touch that one to enable e10s in my FF 54 test environment. I think that difference would explain why I (still) can't reproduce it, even enabling e10s and testing with your NoScript config.
You're most likely aware of this already, but in the unlikely event not, maybe something to think about:
Your export file you PM'd me has ABE enabled but no enabled ABE rules. If that is your actual primary configuration, and not just something you did as part of troubleshooting this, then you would have no significant security difference just disabling ABE entirely.