Thanks, I have figured out how to run the mic wire from the frame to the radio in the meantime. I found a video explaining how to replace the dashboard speakers which was very helpful in the process.
I fully agree with your assessment of the installation instructions - I’d even argue that they are practically non-existent, as they only consisted of one page showing how to connect the UConnect unit to the ENG-Custom module. Moreover, the manual omits the very basic information you provided: using the Back button to switch between UConnect and CarPlay.
I, too, was in contact with their support, mainly to find out how to connect the OEM rearview camera to the module. Have you got this to work? Apart from the camera, everything seems to work flawlessly at the moment. What kind of software issues were you struggling with?
Lastly, I attached a pic I took of the module installed in the spot behind the UConnect display that you had pointed out. Maybe this is helpful to someone else planning to take up the challenge.
Oh, and one more very basic question: how did you manage to attach the lower part of the A/C unit to the console again with the two metal clips? Somehow, they keep falling out for me.