Matt, even though you have a midline, the up & down buttons should move you through the various parameters on the midline display; range, economy, average speed, time etc. I think you need to check your VCDS coding in case you've missed something.
I did exactly the same with my car, and before I put highline in, the right side up/down buttons worked the midline dash. The star button mutes the RNS510, and the phone button doesn't work, as my Skoda bluetooth would play with it!
It's either in the coding, or your central convenience (but I doubt that).