Also, let's put rubber to the road:
Is "toe-walkers" a real actual preference that is materially really quite important, to a person present who is real and not theoretical, who does not exist for the sake of argument?
I know plenty of people who are particular about paws vs human feet vs hooves vs other kinds of feet. Some people into foot play will be specifically searching for paws, or specifically equines with hooves, or specifically furries with human feet because they're into furries bit not paws.
I haven't met someone yet into footplay who cares strongly whether the paws are plantigrade or digitigrade. Toes vs heels has simply never come up.
I'm open to the idea that such a person may exist. Are there many? Is this a common thing? (And since many furries don't know much about animal anatomy and wouldn't know whether a lizard or bear walks with heels on the ground or not, is that reliably useful enough to distinguish?)
We are creating a system that primarily exists for searchability for what you want, and secondarily comparison, but not for strict technical accuracy.