...all my RHEL OS and applications are in english; how come this error message in portuguese?
not all of them ... this one for example uses $autor instead of $author, clique instead of click, and livro instead of book ...and that's just in the snipet you've shown us.
so if 3 out of the 25 lines you pasted here have portuguese in them, i'm going to go out on a limb and guess that *somewhere* in the rest of your application, there might be some more Portuguese, maybe even setting the LANG so that error messages from perl are in Portuguese.