On the "compacting" option - there may be another example of a 2-PART CFX piano that this is already done with - but you can take CFX Concert and turn on all the elements of PARTs 1-2. This gives you a usable amount of velocities for the G#5-G8 keys (actually lower than G8 max, since the usable notes top out at a lower key than G8). Unrelated to usable notes (by sound): some nudging of the velocity ranges for G#-G8 may be in order. The low-end of the keyboard is unaffected so this allows removing PART3. Then if you do not find the key noises to be important - deleting PART4 allows for getting down to 2 PARTs. Since the key noises do not take up many elements - they may be able to be "stuffed" into a different AWM2 PART that is also under utilized in the context of a performance.

There are loose ends to tidy up when doing this (cannot arbitrarily stuff elements, such as the key-off noises suggested, into an existing PART without paying attention to the PART-level settings and how they may change elements that were designed for a different PART environment) - but it may be possible to at least scale down CFX Concert to 50% resources in terms of PART utilization without significant loss of piano response.

Of course if you do find another AWM2 PART home for the key-off noises, you'll want to target a "bread and butter" sound you use often so you do not have to create lots of different PARTs every time you want to add in the key-off sounds in a compact manner. Depending on how you would use this kind of hybrid part (original sound + CFX key-off) it may not be possible, if every performance is unique in terms of instrumentation, to avoid having to construct a different hybrid part every time.

I'm not saying it's a great way to go - only that it's a possible way to go with what's provided.