Good find Sean.
From my side I’ll just add that if you grenade your own mortars and kill the crew (it extends to any kind of support weapon), you can build another one and recrew the one you grenaded (so you end up with 2 mortars).
I don’t think if anything can be done with this.
Same goes for the decrewing/crewing tanks, but most (if not all) limited tanks in wikinger probably don’t have option to decrew, so it should be fine.