It really means "shoe", but it looks logical that "calceus" was a sandal, as it was Roman shoes.
From "Calx" meaning the heel and, as a metonymy, the foot.
A sandal was "sandalium".
English "sandal" -> from French "sandale"-> from Latin "sandalium" -> from Ancient Greek σανδάλιον (sandálion), diminutive of σάνδαλον (sándalon, “sandal”) -> Probably from Arabic Arabic صَنْدَل (ṣandal) (=meaning sandalwood, French Santal, Italian Sandalo, Latin Santalum) -> from Persian origin.
Because the sandals was originally made, not from leather, but from wood.
Conclusion: I will try "sandalium" to translate "shoe" in English sentence.
That's cool they changed the word "shoe" to make it "sandal", it makes use think about what was a shoe in the ancient Rome.
From a male perspective a shoe was for me always some closed footwear. And anything with open toes a sandal. Not going into slippers, boot etc. But considering female footwear and those straps with soles they call shoes, basically everything is a shoe and only adilettes are sandals. Actually vague terms.
a) This is the only sentence in the bunch that uses the word "sandals." Everything else gave "Calceus" as "shoe." The hovertext lists both, but this one won't accept "shoes" They can use whichever they want for a primary translation, but it'd help to be consistent throughout.
b) I learned that "vult" meant "want" or "wish." Duo won't accept "wish" at present. (both reported)