This part of the game is totally ruined.
Companions literally do not progress at all. I have a surgeon from the beginning of the game, she had 60 medicine, after about 200 days of in-game time she is at 67... I also have scout with 80 scouting... for entire game! He's got an unpassable learning limit. So nice...
None of my companions gained a single level up! We can not upgrade them, we can not control their progress.
They also lack of personality - just a puppets with names on them. If it going to be so, give us a possibility of renaming them at least! The most popular nicknames will be: Dumb, Useless, Nobody.
The only companions upgrade mechanic which works is Mimir with a quest of teaching him for 200 days. I'm actually surprized that it works... He gained 60 SP in a couple months.