At this time both products TTS-1 and Sound Canvas VA are history.

https://discuss.cakewalk.com/topic/74606-end-of-life-for-tts-1/
If you have older Cakewalk/Sonar installer, John Vere explains how to preserve TTS1.

Roland Sound Canvas is a much better, more flexible GM synth in my view than TTS1.
TTS1 was not updated in about 15 years.

There are not many choices left that you can officially purchase at this time that support GM/program changes and are flexible. Halion Sonic 3 was the last "all in one" professional solution. New Sonic that came out last year has issues with GM / program change playback.

VSTSynthFont that was included at some point with BIAB likely the last man standing.