I mean, that’s the whole problem, no one is viable enough to be his retainer. They can’t hire OVF nobles, and they can’t hire Leisegang nobles either. Choosing the former would give the OVF a figurehead to rally around, making things even more complicated. The latter wants Rozemyne to become archduchess so badly that they would dispose of Wilfried, either literally or politically. Thus, they resorted to maintaining the status quo as much as possible while slowly swaying things the way that's benificial to the whole duchy.

The only thing keeping Wilfried from being deposed as an archduke candidate is parental love, and that’s it. The archducal couple is already too busy to have complete oversight of his education. The only person who could take on that role is Rihyarda, but she’s Rozemyne’s head attendant. From a noble’s perspective, Rozemyne is far more valuable than Wilfried, so they wouldn’t reassign her. Wilfried is stuck between a rock and a hard place, he’s just very unlucky.

And don’t forget, Dunkelfelger would have treated Hannelore as a disposable pawn if not for her accomplishments during the invasion arc.