You're right, "Tiu vorto havas pli ol unu signifon." is a more usual sentence.
I do not understand your sentence.
Duolingo's sentence refers to words such as "leave", which has more than one sense (to leave home = to go away, to leave a book at home = to make the book remain there) or Esperanto "lasi" which can mean "to leave (something somewhere)" or "to let (someone do something)".
Those words have more than one sense - pli ol unu sencon.
I meant the english word sense instead of meaning, the esperanto word seems fine to me