The next thing for DL is to learn how to spell proper British English...
I think you should have the option for British or American English and European or Latin American Spanish as well as European or Brazilian Portuguese before you start a course. In the UK where I live, it's colours not colors and grey not gray. Duolingo needs to learn British English.
Mas bien, "un idioma." Lenguaje refers more to figurative language, or literally speech. El lenguaje de sus poemas es muy complicado y me cuesta entenderlo. - The language (choice of words) in his poems is very complicated and it's difficult for me to understand it. Hope that helps!