that thing is so fuzzy that you could do a fairly bad drawing, not one that would ever pass in a Japanese class or test, but it would still be able to suggest the kanji you are looking for.
Yes, it would recognize it, but it would assign to your drawing a very low score. If the score is lower than 50%, it might be even recognizing a completely different kanji from the one you were drawing. One thing I like in this module is that it forces you to respect the symetries, the quadrants... If you get strokes of the bottom half that are drawn mostly in the top half (or right/left), then your score drops very quickly and it will just not recognize at all what you meant, you have to try again.
If I do
級 in quick strokes of my finger, I get 66% . It's recognizable but very bad. Is that a E? a D? Or even C, since it's unmistakably recognizable? The American marking system is a very mysterious thing to me... But here it would be advantageous, because showing a relatively high percentage gives the false impression that 66% is good. (In France, if a child gets 13/20 at his high school math test, most parents would be satisfied, some would start thinking that their child will soon be an engineer...).
Slower strokes get me to 86%
Slow and careful strokes get me to 99%
If anything lower than 50% gets F, then 50 to 65 for E, 65 to 75 for D, 75 to 85 for C, 85 to 95 for B and more for A, you would probably have something about fair. It would have to be tested and refined, of course, but I think when the percentage is over 75% or something close, it would pass in a school test (C is "barely passed", right? Just like our 10/20?). Or maybe I'm too generous with my own drawings, I have no idea how good a drawing has to be to pass a test. Maybe 85% corresponds to the minimum pass grade.
It might be easier to just switch to the module that gives this score (Bayesian probability) to your drawing rather than to adapt the current module for people drawing with their fingers on a rather small surface?
Again, I don't think I'll practice kanji handwriting much, but that's my 2
銭 on the subject.