I may have made it sound like I know what I'm doing.
Nothing could be further from the truth
So, I tried opening standalone AL4 and the Nanokontrol2 is not mapping any parameters.
I clicked on the gearwheel icon in AL4 / Midi Controller > Enter Assign Mode. Using 'Generic Midi Controller' template, Midi Channel All.
According to Korg Kontrol Center rotaries are CC16-23 and sliders are CC64-71.
The first 4 of each row of rotaries are coloured red and show the matching CC number to show that they are assigned (correctly).
Something weird is going on with the Nanokontrol as sometimes it needs to be re-plugged (restarted) when switching DAWs.
In this case nothing I do seems to make it connect in standalone mode.
Just to confirm, I opened the Korg Nanokontrol2 default settings, wrote them to the device, then opened AL4 standalone.
I've got VTS2/3 and AU formats installed. How do I know which one is being used?
In MainStage it will only be AU format, that much is certain.
I've now tried the settings again in MainStage and found that something unintuitive was happening with already allocated mappings.
The controller was not overriding existing mappings and so I had to manually delete those to make them available.
They do now actually work, but to make matters more confusing, in MainStage copying a patch does not copy the midi assignments so they have to be manually mapped again.
Maybe there is a better way to do this or another option in MainStage I have not seen yet.
Goddammit midi controllers are not easy to set up.
In Bitwig, the native script works nicely between mix mode and device mode, but only for macro controls in device mode.
Native controls in device mode don't seem to work either, at least with the native script (which I think is the Driven by Moss one).
Sometimes I feel I am either too dyslexic to figure this arcane stuff out, or I should just go all hardware, or maybe the devices are really not designed in a way that works well with different setups... :p