If Kant's idea of the formless sublime is a "viscous contingency of empirical phenomena" (which I interpret as a transcendental real that lacks ultimate logical foundation) and negative representation is the 'raw' noumena/substance/dedomena that is represented by positive data/theories/schema, then they are analogous but not identical.

If they were the same thing they would have the same terms. That difference lies in the context of a third element which is missing from your question.

Negative refers to process and formlessness does as well

Thanks, Gregory.