Hi, you might consider using the Blend Container as a container for your different instruments,
then create a Blend Track and use an LFO set to Random mode to pick a different instrument to play for each note.
More directly but Hacky's approach is to create a PD+Heavy plugin that outputs an RTPC value to drive the Switch Group every time a note is played,
enabling random selection of content under the Switch Group. However,
I think using Random LFO should be enough for your needs :)