We consider Friederich’s recent Q-based interpretation of quantum mechanics. We argue that the interpretation is incomplete by providing distinct microdynamical models that give rise to the same bulk evolution of the Q-function. Since there are apparent foundational differences between the ostensibly distinct interpretations suggested by the different possible microdynamics, Friederich must either commit to a single microdynamics, or else provide some reason to consider the distinct microdynamical models as physically equivalent.
Previously developed ``stochastic representation of deterministic interactions`` enables exact treatment of an open system without leaving its native phase space (Hilbert space) due to peculiar stochastic extension of the Liouville (von Neumann) equation for its statistical operator. Can one reformulate the theory in terms of stochastic ``Langevin equations'' for its variables? Here it is shown that in case of classical Hamiltonian underlying dynamics the answer is principally positive, and general explicit method of constructing such equations is described.