Cool idea, I think you would need a very large sample size to verify something this intricate.
Difference in manual dexterity on a task like this could be pretty wild in terms of overlap with other issues. Interesting piece of evidence.
Do you have coactivation firemonkey?
I’ve never done the tests mentioned in that research article.
What I can say is that my manual dexterity has never been good. Although never officially assessed diagnosed as such several (mental ) health professionals have mentioned dyspraxia.
Poor coordination and balance + odd gait + fine and gross motor skills deficits, sums things up well.