Yes, it is like what I wrote. RPC in epsilon and beta planes tracks the REAL position of target (V is not needed for this). So the change of epsilon and beta coordinates in time is known and it means REAL target's track. {In CW mode we do not know the target's distance, but it is calculated by CVM from RPC position changes and measured velocity}.
When VGPO is active, then the velocity measured (V) at one moment begins to rise rapidly, but the RPC will still track target (epsilon and beta) and this "small" change of position of RPC (respective to target's REAL position and thus REAL speed which is lower than measured velocity) will not correlate with measured apparent speed and when the change is bigger than 4,6kHz or 0,8kHz then the AS to RU (along with velocity gate shift) switch will happen.

In any case it would be very very great to have this simulated. And also other such advanced scenarios, you can learn the system very deeply when you dig in such things.