FabFilter iOS plug-ins do support midi learn when the Auv host is Cubasis, but that functionality isn’t available when using Mackie on a control surface.
100% agree that the Cubasis experience is vastly enhanced with an X Touch!
We’re currently missing (IMHO) 2 key areas of Mackie support:
- Track meters
- Control over plug-ins
May I suggest you visit the following thread and add your vote?