I would like to thank you very much for your helpful comment!
So, as you wrote, seems NR2X can be sequenced the way I need (4 voices/sounds separately to each OT MIDI track after assigning to different MIDI channels).
That’s really good information.

One question more regarding audio cables connection. Can I connect them from NR2X audio outputs directly to OT audio inputs, so OT will play them on it’s audio outputs (and headphones output as well) together with it’s internal tracks ? Or do I need external mixer gear to consolidate NR2X and OT audio outputs?
I have not much space for additional gear, so I want to set up OT as a main hub for sequencing, but also as a “mixer” with 1 audio output ( for internal OT + external MIDI tracks).

Do you have any other remarks regarding NR2X? I like it’s direct and simple access to all parameters, without menu diving and nice sounds. But, I am not experienced with this, so each remark will be priceless for me.

Thank you in advance!