I can't currently link you any concret Post, by any VSL-guy but as far as I know the reactions about speechcolor improvements of the Viennese Voice-ssamples are at least ambivalent. While one can read sometimes "there will never be an wordbuilder functionality for the Viennese Voicesamples", there have been on the other hand sometimes indications, that it is not that unrealistic to get similar Samplesets for the missing vowls once upon a time. Of course it is still much work and obviously other things will have presumably a greater priority,
At least it seems to me that one must not completly rule out the possibility to get more vowlsets for the voices sooner or later which at least seem to me not that unrealistic as a complete Wordbuilder. However I myself at least would appreciate this addition very much.
But it is kind of funny to discuss this matter while they just announced such an essential vast an overwhelming project like the complet new recording of an Orchestra on a completly new level. So let them do what they are able to. It always was worth waiting for.