Based on previous Lang Belta words we have seen, "wala" seems to be a base word meaning "person." Because Belta is a creole language, it makes sense that anka would mean "anchor" due to the similar sound to the English word. So, I would say ankawala means "anchorperson." Oksana and Camina are obviously in relationships with other crewmembers as well as each other, so I doubt ankawala means wife or spouse. It is more likely that this "anchorperson" relationship is a futuristic polyamorous term that refers to someone who is a romantic partner as well as being the captain-leader of a ship family who holds them all together/keeps things stable like an anchor.