When is 3.1 coming out?

The correct answer should be ‘soon’.

Simon_NI wrote in his post from February 19th, that Custom Chord sets would be comming in a few days:

As you may have read from Chris, we have some updates coming to Maschine. Following the release of Maschine v3 software last year, we’ll bring Custom Chord sets – another highly requested feature to Maschine 3 in the next few days after a successful beta-testing period.