An interesting subject. Wish I had something useful to add. The bus width limitations in Cubase keep it from exceeding 4-channel FOA. I suppose you could try exporting it as quadro, which would likely come out as some sort of wav file. The B-format is related to the wav format. Adding a quadro output bus would be part of that approach. I suppose you could try exporting 4 mono wav files (1 per channel) and hope the video editing software can sort it out. It looks like Premier Pro can deal with 4 channel wav files. (Premier Pro and youtube) You’d need to get the channels in the correct order.
Another possible tactic would be to export a 4 channel wav and convert it to B-format using ffmpeg. like this? While youtube isn’t likely what you’re aiming at, b-format is.
I’m a bit surprised that the waves plugin doesn’t somehow offer an export option itself. I have yet to select ambisonics plugins. The waves ambisonic plugins look good (and I’m considering them). For now, I’m leaning towards dearVR (plugin alliance). I’m not sure they have B-format export either! Luckily, I’d most likely export as binaural anyway. There are other options, or course, but one likes to keep it cheap. It may be possible to do something with FB360 (free) or Reaper (cheap). I’m glad to have other things to do while this technology has a chance to mature.
Best of luck with this. Please post if you find an answer.