I assume these small problems in the interpolated instances are rounding errors. When I select a control point, move it slightly with an arrow key, then move it back, the problem resolves itself — rounded to the nearest appropriate grid coordinate, I assume.
If that’s the case, is there any way to automate this process across all the glyphs without opening each one at a time? Or am I concerning myself with something so inconsequential that fixing them isn’t worth doing?