MIDI mapping on a Roland E-70

I’m using a U2MIDI v2 USB device where I’ve connected my Roland E-70 to the PC and it works perfectly. It’s just that the rest of the buttons (not the keys) seem to be assigned quite randomly or messy to random keys and program changes on the VST instruments I’m using. I’ve tried using “MIDI learn” but it only seems to recognize my modulation/bender bar, on some plugins. The rest of the buttons stay mapped to whatever they are mapped to, and I can’t seem to re-assign any of those.

I’ve also tried to use MIDI learn via the generic controller in Cubase but it doesn’t respond to anything on my keyboard there. I think Roland E-70 isn’t very supported there, since it’s supposed to work perfectly for many other synths/devices, but there has to be a way to figure it out right? I haven’t found any very related sections within any roland forums for such things… so quick summary: the modulation/bender bar works for some things, the rest of the buttons are assigned randomly, and MIDI learn doesn’t learn, only sometimes the modulation/bender bar.

Anyone knows how to solve this with a Roland E-70?