So, I wasn't able to login via TOR via the purposefully created .onion address. Also, sent an issue report via non-TOR login about this, but never got any response.
Note also that this seems to mean to me, that there may be people who are cut off from FB via TOR same as me, but who don't even have a way to notify FB about the fact. And thus not having any chance of having the bug fixed.
It sounds like the test was just broken.