The Scaler internal sounds appear to be held as ‘flac’ files with two tone spaces, each over 5 octaves. The rendering engine would presumably have to be enhanced to do tine constant pitch shifts. They have said they are looking at the rendering engine, and improvements are expected in future versions, but alternate tuning is probably a big step.
However, the main point here is surely that Scaler is “mono-timbral”, and most users probably move midi created in Scaler to a DAW to assemble a track together. So this means that all the synths on the DAW track would also need to support alternative tunings. and this may prove to be a barrier.
Something similar was discussed in
The only product I have which does this is Omnisphere, which is remarkably flexible in this regard.; it supports A= 420 - 460, and has about 60 tunings other than 12TET.