So Eutropia's whole drive to overturn primogeniture means women will be able to inherit property and aristocratic titles... but there are female NPCs throughout (especially in Crownfall and SSS) who HAVE property and aristocratic titles (see Baroness Voinum and Dame Crabbe in SSS especially). How did these NPCs inherit them under male-only primogeniture?
How did these NPCs inherit them under male-only primogeniture?
It's never explicitly stated anywhere. The most common interpretation is that the law had already been loosened to allow women to inherit land and titles in some circumstances, but the office of Grand Prince remained fully closed off.
The male primogeniture law this AP is about is only in regard to the sovereign title. Other titles may have their own inheritance rules.
Compare this, for example, to the British peerage. In general, inheritance of titles follows the rules of (in CK2-speak) agnatic-cognatic primogeniture, but many titles have special stipulations that were defined when the title was created.
For example, in the most cases, when there is no male heir, a title falls to the oldest daughter, but other title have a rule that if there are multiple daughters, the title falls into abeyance, and no-one will be able to hold it until a single heir emerges, which can take centuries, such as with Cromwell barony which was in abeyance for more than 400 years. Other titles cannon be inherited by female heirs, and others again treat women as equal heirs.
What I'm saying is, the law just affects the imperial title, and there is no rule that says it must apply to all titles in Taldor, especially with Taldor being such an incredibly old and byzantine monarchy.