"Putting extreme Ranaldite lawyer glasses on"
Now, technically speaking, if I am reading Article 5 correctly, and I may actually not be?
The colleges can bestow rights into any initiates, they do not technically have to be capable of wielding arcane magic, just to be legally part of their organization respective to their magic researching hat.
Now, this lawyering actullt seems completely useless, as it, at best, allows them to hire some nonmagical researchers, as no priest would desire the divided loyalty, plus, it may well be that some will disagree with that proposition anyway on the grounds that it is too legalistic and obviously not what the articles intended, that initiates means magic users, that priests cannot be initiated into colleges etc. etc. So in practice, that loophole has been completely useless until now, because even if that reading is possible, it is also politically unfeasible to make.
But in the off chance we can get Sigmarites to make that precedent in some way, maybe by leaning into our dwarven contacts, wellllll... no one will actually disagree that yes, priests can be appointed magisters and study magic if the colleges and the priest agree on such an appointment, as the colleges have the right to grant that right. The priests wont disagree because the greatest opponents of the colleges gave their stamp, and even if worst comes to worst Sigmarites still have 3 votes in the elector meeting, and the colleges won't disagree because it gives them more legitimacy and authority, and anyway, they are in full control in what permissions they grant to initiates according to article 5.
Now, of course, the pie in the sky here is getting the Sigmarites to back that horse, which even with our status as Dawi will be hellishly hard, and not to even be attempted before diplo 20 at the very least (even then, our status is the only thing that even makes it a remote possibility), but it certainly sems like an avenue that exists.