Hi Macker,
thanks for the comprehensive explanation. That's a pity that there is indeed no workaround, yet.
In principle the dimensions of the Synchron Player seem quite powerful for realtime control, but I likewise don't see the advantage of this "solution" to send two events instead of a single (program change) event to select articulations. In particular since the number of articulations in present Synchron libraries is smaller than in the old VI libraries, so that 128 program change messages would be more than enough.
I did not even realize the problem with unassigned program change messages you mention. This sounds like a bug that they should be able to fix without too much effort. However, the fancy auto-rescaling they implemented in the Synchron Player seems to be intentionally designed for not more than 20 vertical slots, and therefore I don't expect them to introduce a scrollable list as in VI pro.
This would leave the second potential solution. I am not sure if I made myself clear, but the idea is that the same Midi message switches several dimensions simultaneously. E.g. in case of program change events the first ("bank") dimension would switch depending on whether the program change message is in a certain range of values (e.g. 0-9 -> slot 1, 10-19 -> slot 2, ...) and the second dimension depending on the exact program change number.
For this it would merely be necessary to implement the selection of slots depending on ranges of Midi events (notes, controllers, program change messages, ... ) of a specifiable length. This would be very flexible, and, as an extreme example, with 128 values one could switch up to 7 dimensions (with 2 slots each) simultaneously - or anything in between. In case of key switch notes, choosing the ranges to have length 12, one dimension could then likewise be switched by the octave of the note and the second one by the particular key (in case someone wants to dedicate an entire keyboard to key-switching).
This does not sound too hard to implement and I hope this will be done in the future.