Probably already been suggested, if so just ignore, but if not, whatabout making a Qx type expander that is always in CV Assignment/Matrix mode? Don’t know if it would work as I’m not that smart and don’t know how it all works. But if it would, it could be the same size and form as the Qx but instead replace the outs with the same type of lit buttons that are on the Quadrax for each channel and cv input, with the same functions as in CV Assignment mode. So same functionality but just separated from all the button combos on the main module, which also would create a better view of what is going on in the matrix as it would no longer be hidden. I would buy it in an instant as I don’t use the matrix as much as I want to.
There’s 4 CV inputs, 4 channels, and 4 destinations per channel so you would need 64 controls to represent the entire matrix. It would have to be a pretty big module 
Very big indeed! I was thinking more though that the way of assigning everything would work the same way as it is now. So not representing the whole matrix, and still needing to choose which channel and destination I’m assigning which CV to, but that the whole CV have assignment process could be separated from the main module for easier and quicker access