I was about to post something similar. To me it seems like Cover's vaunted HR kinda messed up with Council. Not in getting talented and cute young women, Council/Promise is probably one of my favorite gen of universally likable talents. But maybe temperament, personality, work expectations and stage in their life.
For example I used to work in a quasi government agency setting and noticed they would often decline to hire young and ambitious applicants, or those from high paying industries, like oil and gas or tech startups, in favor of the more agreeable stable older ones. Those types tend to bail fast or are not suited to the plodding nature of government corpo work. For Holo, each talent leaving is a huge scandal and damage to the brand so they need to minimize that. In fact I'd prioritize it.
We'll see if HR learned, and Advent and Justice are better fits. By now all the applicants know about the large "homework" load, constant flights to Japan, and all the idol stuff. All the new girls seem to be grinders and many experienced hardships, failures and long periods of no success.
Tl:dr hire more hags