I would say definitely not, just the opposite. In the idea of "ineffable language" and concepts "which are indeed felt," this appears to show Kant in his "sentimentalist" phase, when he was influenced by Hutchinson and Shaftesbury, et al.
He made a radical turn after reading Hume, once translated into German in maybe the late 1750s, not sure. To answer Hume's skepticism he felt it necessary, indeed urgent, to find some basis for moral principles in critical reasoning rather than authority or any theory of "ineffable" moral sentiments.
This arrival at his categorical imperative by means of critical reason, while also compatible with empiricism, is in many ways the centerpiece of CPR. So, from all appearances this quote seems plucked from his "dogmatic slumber," exactly what he had to jettison to write CPR.
Unusually for a philosopher, Kant does mark the moment of the turn in his thinking that led to his mature work, his pondering of the implications of Hume. So there is, at least in Kant's telling, a before and after. So a simple chronology should provide an answer to your question. Aside from that, I see nothing in this quote that foreshadows CPR.