I work mainly in first-order Ambisonics, and have done for fourteen years. I’ve simply got used to working with four mono files in a montage with inappropriate channel names… When my editing is complete, the montage can write out multi-channel B-format (or quad) files as desired - but can’t read them in again! Some other things I cannot do in WaveLab, and some I’d expect to work don’t at present.
However, it has been stated pretty officially that work on supporting multi-channel files is under way. I guess it has been harder work to re-engineer the core of WaveLab for this than had been hoped, as we had been led to expect that version 10 would introduce multichannel handling. This didn’t happen, sadly, and there’s no indication how close it really is - it could be in a 10.1, version, or 10.5, or not until 11. I seem to recall that the montage was introduced at a point release rather than a major one, so who knows?
But yes, WaveLab is now the only program in those I use which still has this restriction. SpectraLayers now has multichannel handling, and most recently iZotope RX got there (though annoyingly restricted to “traditional” surround layouts). So the pressure’s on, and I really hope that WaveLab will get there soon.