Yes, I know what you're (probably) thinking: AGAIN?
It's been a long road... Back on the first attempts we had some glaring issues that were easily noticed (such as accounts without email addresses causing some weird behavior) but on the subsequent 'shots' the issues were getting smaller, quirkier and harder to discover.
The latest one in particular wasn't about the forums frontend or anything on the 'member/user' side, but it was something more from 'behind the scenes'. The forums seemed to work fine (at least to us) but the backend wasn't exactly working as intended. Props to Stritix for finding the cause behind the weird problems we had.
So... yeah. You already know the gist - If you had vB-era (late '06 ~ '11) account on SFGHQ you can log back in with your old credentials (if you remember them - or you can use the pass reset function). If you had a 'SFGHQnited' era account ('13-'14) the same applies - account should still work. If you made a new account during the 'weird issues' period (Sept~up until now) then it's gone so just make a new one.
NOTE: Regardless of your account's age, I recommend changing passwords so that it updates to the newest hash corresponding to the newer forum software.