That’s the main takeaway here and it’s been confirmed by support as well:
I tested the modulation routing on my unit today and I can confirm the behaviour you documented. I’ve added this to our bug list for review so that the delay time can be key-tracked with each note you play.
I can think of numerous ways this could be implemented in poly modes as well: last note, lowest note, highest note… just any change to the delay time would be nice…