Multi-touch moving two submasters at a time

The virtual fader tab doesn't support multitouch functionality

Doesn't this seem like one of the most basic things that need multitouch functionality?

You could try making a magic sheet with all of the faders you are looking for. You can map each fader to a fader number and use the fader configuration screen to configure them, just as you would with the virtual fader tab. I'm not sure if magic sheets have multitouch functionality, but it might be worth a try.

Magic sheets do have multitouch but use it for other stuff, e.g. pinch gesture for zoom. So no, you will not get it to move multiple faders there either