I believe there is a personal element to all of knowledge, so that it is not ever to be restricted to propositions. ...
I agree there is a personal element to knowledge - but it does not follow that knowledge is anything more than propositional. Any non-propositional knowledge would be unknowable (at best) and utter nonsense (at worst).
Please tell me one non-propositional truth you know.
However, the reformed have denied the mystical idea of knowing God immediately.
Could you explain this? First, what do you mean by immediately, and second why is that mystical? Is not the knowledge of God, his character, not immediate knowledge.
JonhV mentioned the knowledge of interpreted dreams. This seems like immediate knowledge so maybe I don't understand what you mean by "immediate".