what is the significance of knowing what your Vmu is?
There is no significance in knowing it as an operating pilot. Nor is there any significance in the pilot knowing what Vef, Vloff, Vmcg, Vmca are, because they are NOT operational speeds. They are of extreme importance to the Performance Engineers in deriving the day to day practical speeds, such as V1, Vr, and V2, after applying suitable margins and tolerances.
As for Venr, perhaps appropriately labeled as Vcl, Vfto, V4 - The final Takeoff speed following engine failure with the aircraft in the Clean configuration, and the remaining engine/s set at Maximum Continuous Thrust / Power.
Regards,
Old Smokey