yes, sounds like a sensible approach. Hausdorff considers the worst of all shortest distances. a good measure. I don’t know how much more you’d wanna calculate from complete nearest neighbor information for both sets. that could give the user detailed feedback on where they drew pretty accurately, or where they deviated entirely.
if the user doesn’t draw over the template, the result could be shifted, rotated, or even scaled. perhaps run a few iterations of Iterative Closest Point, to try to remove any shift or rotation, which would make the scoring less harsh… if there’s a chance the user drew something scaled up/down, compensating for that too maybe.