To clean up these groups of beasts is a simple matter for Leila. But in accordance with her nature where she does not like to involve on matters outside her jurisdiction, she has some misgivings on acting on behalf of the people she took under her wing. It just felt so wrong if she did do something (especially the violent ways) towards these creatures.
In Reilas there are simply too few creatures and creatures whom she has given her care and affections. And all beings are careful in provoking her and stir clear from seeking her treasures unless they are intent on angering her. Her infamous myths and lores have said too much of the aftermath of her wrath for them to be conscious of their ending might be.
It also helps that Reilas recognizes god and goddess that most people do not dare to anger them without any reason. And in return to their reverence, they got these entities' protection and blessings. Thus making resemblance of peace and balance in that world.
