The frequency peice is interesting and I guess could be measured. But not sure how you'd model that to good results/forgiveness. What is forgiving for you might not be what is forgiving for me because our mistakes are not the same. Too complicated
Modelling would be difficult. I guess it would take folks with equipment that could find the string's natural frequency on the bow in question. Add weights to specific places( experts might know of nodes etc.) shoot some bareshafts and get an area mapped on the target.
Chnge the weights and/or positions and repeat. See what effect there is on the bareshafts' landing zone.
I don't think the up down changes that could be speed related are the issue, but a chrono might help to run alongside the tests.
I might expect a change to the left/ right impacts of the bareshafts or possibly a change in group size.
Changing string weight I think might show up on the chrono, but if the thinking has any merit I am expecting something to happen suddenly at a particular weight /or position of the weights on the string.
Perhaps at some point the string vibration is naturally out of phase with the swing rate of the arrow shaft, and gives the arrow a straighter path as opposed to an elongated S shape.
Forgiveness is something I have heard about; it isn't something real as far as I know. having seen videos of situations where wind causes items to wave about to the point where they tear themselves free or to pieces, I can see that vibrations can have effects that might be better reduced for our own good. Perhaps string vibration could be put to better use as opposed to seeing it as bond to happen just as arrow flex is bound to happen
We spend time matching spine to draw weight. I know some compound bows fit weights to strings in strategic.... perhaps there is some connection.