You should definitely report it if that was the case, although I didn't have the woman's voice in mine, so it might have been fixed. But Duo won't accept a word jumble as correct, although if you can't make it out correctly (whether the error is yours or Duo's) you may have no option but to put it.
I think slacks was more often referring to woman's pants, but I think that's mostly because slacks tend to be more informal and traditionally the whole concept of pants of any kind was informal for a woman. Trousers in the US I have mostly heard only for the category name. I think my Grandfather used to refer to what he was wearing as trousers, but not mostly. Both of them seem on the decline in the US, although trousers was never common here.