The connectors are in with hot glue, so a tiny bit of hot air (even a hair drier held pretty far back) OR a drip of acetone will cleanly remove it without damage.
MCU is just “Micro Controller Unit”.. more info on this issue can be found in this thread; MCU 'extra_mcu' shutdown issue
The second error is the stepper driver for the extruder filament feed, the error is mentioned in more detail on klipper discorse here, but it seems to be mostly the sort of thing your already aware of TMC 'stepper' reports GSTAT: 00000001 reset=1(Reset) - Knowledge Base - Klipper
I’d also make doubly sure the enclosure you added isn’t causing the Klipper board, MCU or Stepper Drivers to simply get too hot, as this former of those was an issue right out of the box with my SV07, and it was completely solved by sticking a tiny little fan to ensure fresh air made it over that board (which is part of the touch screen on SV07, rather than on the mainboard next to MCU as it is with your MAX).