Yeah, I'm experiencing a similar issue that the Aux commander doesn't seem to show up. He seems to be sequence broken after the forest monster that you fight with the archer dude. I am on version 0.34 if it helps.
Ironically I seem to have triggered his corruption level 10 cutscene outside his tent but I can't seem to find the Actual Aux Commander after that.
So there are three possible scenarios for this:
1. I somehow missed him in the quiet meadow
2. I accidentally broke the sequence by farming level 10 corruption.
3. This bug and disappearance happen on a fresh run from 0.34 (I lost the save files from my earlier versions and had to try again.)