If setting a quantise preset using 8th notes with a 40% swing you get this:
However, if I want to use 16th notes in the track, I need a 16th notes grid, but then the ‘swung beat’ doesn’t line up with the 8th note. No amount of swing in the 16th notes grid will line up because changing swing moves the 1.2 note and the 1.4, not the 1.3. So how do I make a 16th note grid based on the 40% swing from the 8th note preset?
Trying to read between the lines here …
Was that 8th Swing preset created from just those two notes, as seen in your screenshot? If so, you need to create a MIDI part that has notes on all the 16th beats (including the ones you want to swing, of course ), then create your Groove Quantize preset from that .
(Start with that existing 2-note MIDI Part, change the quantize value to regular 16ths with Snap On, of course), insert new notes, to fill in the gaps.)