Simeon from the Firefox Add-ons team here. Sorry about the rocky experience. I realize this is a bit late for your situation, but earlier this year the source code submission docs were updated with information about the default reviewer build environment[1].

It's not a huge improvement, but it sounds like one thing we could do to improve the communications process around build errors is to include a link to this documentation in the notification email sent to developers. I'll create a ticket for this now.

[1]: https://extensionworkshop.com/documentation/publish/source-c...