Speculation
The visiting schools are sketches, so fans finish the painting
Beauxbatons and Durmstrang arrive as entrances. Most claims about their daily teaching are fan work.
A tournament brings two schools into the castle for a year and then sends them home. What we are shown is procession, rumor, and a few students under pressure. From that, fans build languages, uniforms beyond the visit, and whole curricula.
Some of those inventions are delightful. They become a problem only when a wiki tone promotes them to fact. If the page did not assign the homework, this journal will not pretend an interview in your head assigned it either.
Speculation is welcome in the margin. It has to wear the label.
The other side
Entrances are evidence of a kind. A school that chooses a particular spectacle is telling you what it wants strangers to believe. Reading that performance is fair. Inventing the Monday timetable is extra.