Okay, I'm lost on the "Q". Even if you draw half of the cross mark first, then go entirely around the circle before drawing the second half of the cross mark, won't the two halves of the cross mark not be 100% aligned since they can't start at the same position on the circle without overlapping? Am I missing something?
Touching a point twice isn't a pen stroke "going back on itself". It isn't retracing a line going back the way it came.
Also consider that if the rules prohibited overlapping even slightly at a point, then you could say the same thing about simply drawing a complete letter O, at least with a round-nibbed pen. You'd have to overlap slightly at the point you start and finish. To draw an O without overlapping you'd need a flat-nibbed pen. And with a flat nib you can draw a Q without overlapping even slightly at the intersection.
Not in the way it's written in this font, but some people write it so the down diagonal stroke of the R doesn't go along the bottom of the curved bit. So it would go up the left line, around the curve all the way to where it meets the straight line like a P, and then continue the diagonal stroke without touching the curve.
Also consider that if the rules prohibited overlapping even slightly at a point, then you could say the same thing about simply drawing a complete letter O, at least with a round-nibbed pen. You'd have to overlap slightly at the point you start and finish. To draw an O without overlapping you'd need a flat-nibbed pen. And with a flat nib you can draw a Q without overlapping even slightly at the intersection.