That EASA notice was interesting reading. Most of the proposed changes to certification of gearbox designs for loss of lubrication operation seem appropriate, but there are a few areas that could be improved.
The most important thing to consider with rotorcraft transmission systems is that the primary function of oil is for cooling the internal components. The amount of oil flow required for "lubrication" is quite small in comparison to the oil flow required for cooling. So the most effective approach to improving loss of lube performance are design changes that improve heat transfer away from critical areas in the gearbox, such as bearing and gear mesh contacts. Or using the recently developed advanced materials for gears, bearings, housings,etc. that can tolerate higher temps.
Another change to loss of lube qual testing would be requiring two or three gearboxes to be tested. And the gearbox test articles used should have been run so they represent the average condition of a gearbox in service.
Finally, there were a couple proposed requirements that seemed a bit optimistic. For example, the Class 3 failure criteria (Imminent Failure) on p.18 states "the efficiency of the gearbox may be reduced by up to 10%.". A decent new build MRGB probably has an input/output efficiency of ~96%. So a gearbox on the verge of imminent failure after the loss of lube test cycle must still demonstrate an input/output efficiency of >86%. I don't think this particular requirement is realistic.