Problem:
The OrcYoungLOW troop type in spawnlist_master uses the scripts/entity/tactical/enemies/orc_young as its Script, even though a separate script scripts/entity/tactical/enemies/orc_young_low exists in the codebase. See attached screenshot.
This causes any orc party in the vanilla game which is supposed to spawn OrcYoungLOW to actually spawn OrcYoung instead.
Solution:
Change Script of OrcYoungLOW to scripts/entity/tactical/enemies/orc_young_low.