Backup your Tai config and any plugins it uses to your PC, then just do a system restore to wipe the account, set it up with whatever account you want, reinstall Henkaku, then restore your Tai config backup and plugins to get your SD2Vita working. Pretty much as simple as that.
Not sure about your QCMA issue (still working fine for me, just tried and I'm on same firmware), could be a number of things (like wrong drivers installed, some config option not set, etc).
But for PSN, no, there's no workaround beyond updating your firmware.
Switching drivers did the trick. Thanks!