While I don’t think there’s a mod for this in particular (and reading over the AsBuilt DB, it seems like this is an option that doesn’t exist natively), I’m interested if OP or anyone else succeeds at this.
I’ve been down a similar path dealing with the ‘popup’ system trying to sort out the Flank Guard function in my C-Max but ran into the same issues the OP did. Either the entire popup system was disabled even for useful popups/alerts or managed to ‘hide’ the popup but the screen could not be interacted with. Or it may have been the latter situation in both cases. It’s been a while since I’ve looked at that code. Unfortunately I have given up on it for the time being with the headaches it was causing.
For reference with the Flank Guard issue: I’ve enabled it to show the parking sensor icon on the rear view camera but it also forces the FG function which has a full screen popup sensor display that normally should only appear when a sensor is triggered at low speeds but with the PAM stuff on the C-Max it pops up immediately below ~5mph even if everything is quiet. It can be dismissed but it is still an annoyance. Here’s a post I made here previously and the second screenshot is the display I’m trying to remove. It uses the same popup subsystem as the repeaters like Volume/Temp/Fan/etc… I have a feeling if a solution is found for either one it will at least give some useful clues for the other if not a full solution.
EDIT: As far as reducing the size, you could potentially check the Fancy Rotary mod? It changes up the style/graphics for the volume/temp repeater so it may have some clues to making it smaller.