(1) I, too, wish to know the answer.
(2) So I cannot give you the answer.
(3) I have only two suggestions:
(a) Please google "Corpus of Contemporary American
English." It gives sentences in which a particular word has been
(i) When you get there, type in "nonsense." I believe that there are
more than 3,000 sentences with that word.
(ii) Do the same for "nonsensical." I believe that there are about
300 uses of the word.
(As you can see, "nonsense" seems to be more frequently used by
Americans than "nonsensical.")
(b) One other thing:
In American English, never say something like: That is a nonsense.
Some of our British friends use the indefinite article, but I believe that
Americans rarely do so.
(4) Sorry that I could not give you more help, but this website tells us non-teachers
to be very careful before answering learners' questions. I hope that
someone will soon tell you and me the difference between the two