Changing the order of the first frame's steps (while still remaining fairly logical / consistent) won't be an option here.
In regards to the builder case, all that was needed is to not perform the foot check on the first step of the first frame.
I'm not entirely sure that the 2px wall case should be changed. If the desire is to change it, then the change would be similar here - skipping the foot check at that pixel on the first frame of the Jumper sequence. To simplify the rule, this could simply be "skip the foot check on the first 3 pixels of the Jumper's first frame". (The head checks and wall checks could remain intact, I believe.) To be clear: This isn't a case of "there's a strong reason not to", just "I'm leaning towards don't change it" and I'm certianly open to changing it if the general opinion is otherwise.