Hi Elias and community,
I created a redmine project on osmocom.org and added some initial information at https://osmocom.org/projects/altair-lte-modems/wiki/Mikrotik_R11e-4G
As can be seen, it's easy to get access to a serial console if you know the pin-out and have one of our Osmocom mPCIe breakout boards.
Happy hacking!