It's back to working flawlessly, at least on Firefox 58.0b4 with version 1.0.24a3 of the extension.
It's unfortunate that there's a two-month gap in support, but I saw parts of the heroic battle the developers had to wage to get the APIs in. Thanks for persisting, developers. I hope you can retain your sanity until FF58 hits the release channel. Two more months!
