Please say which VSTs you've already tried. I don't want to waste my time recommending a load of things that you've already decided are in your opinion "subpar". You can enter things via the piano roll and people have created some excellent music that way. But your PX130 already is a MIDI ...
The "pitch coefficient" effectively works with percentages. A semitone increase is +5.95% so a pitch coefficient of 1.0595 is a semitone up.See https://www.mixxx.org/wiki/doku.php/pit ... _and_notes for a listing of other values.
Steve