@lexxa Hello again.
Re:
Given you are in, as you say, a pickle; it might be worth trying to see if the newer kernel and btrfs backports of our Leap15.1 or Leap15.2beta testing rpm versions will help you out here.
No installer as yet but the following forum thread, and the dev wiki it links to, now pretty much walk you through the customizations necessary from a sever install of openSUSE Leap sufficient to install the Rockstor testing rpm. But the main relevance here is using their newer btrfs backports that I’m assuming will do a much better job of de-pickling your pickle.
Also take great care with using some of those repair commands. You may find that the newer btrfs software in Leap will effectively sort you out. Or your skip_balance idea may end up working there where it hasn’t here. Also be super careful with the leap install and ideally have only the intended system drive connected. Then once all is configure and you have the system updated etc you can shutdown and connect the data drives ready to power up and have another go at it. Our target distro for our pending re-launch is Leap15.2 but that’s still in beta but openSUSE do some pretty aggressive backporting of the btrfs stuff to their kernels so definitely worth a try as there have been hundreds of improvements in btrfs since the last Rockstor kernel update and most are likely included in the Leaps.
Sorry I can’t be of more help right now but that should at least give you a more up-to-date btrfs platform to do the repair and we have almost feature parity in the testing channel so if it does end up sort you out you may be able to hang in there with that install until we release a stable ‘Built on openSUSE’ rpm version which is likely to not be much more time as it goes.
Hope that helps and let us know how it goes.