In the Tibetan dialect of Ali, "Ajia" refers exclusively to his wife, and has almost no meaning of elder sister. It is very serious for Tibetans to mistake their sister for their wife, and it can even be considered as an insult to each other.
Therefore, the landlord should be careful not to use it indiscriminately. Tibetan has its own hidden rules. It doesn't matter in the mainland. If you go to Tibet, you'd better not talk nonsense in Tibetan for half a word. You might get beat up!