I agree, but I think this must be a nuance of the language. Google Translate gives me some contradictory answers. It says that manifestaciones = manifestations (and does not list demonstrations as an alternate), but demonstrations = manifestaciones, and manifestations = eventos, acontecimientos, actos, or hechos. Can anyone enlighten us?
Never rely too heavily on Google Translate. Google sets up boundaries and their automated scripts are responsible for the rest. I suggest checking the Spanish Wikipedia because everything on there is the result of the opinions of multiple editors. Check out this: https://es.wikipedia.org/wiki/Manifestaci%C3%B3n It says "Una manifestación o marcha es la exhibición pública de la opinión de un grupo activista." Duolingo is correct, this is just a false friend, like how "actualmente" translates to "currently" instead of "actually".
It's frustrating, but as language learners it doesn't really help us to think things like "this doesn't make sense, they are confusing the words". Spanish does not come from English (so there's nothing for them to confuse), and we just have to accept that some things are different and learn them. "Manifestación" has a few meanings in the dictionary, and protest is one of them. Here's a good example from Spanishdict; "la policía hizo una demostración de fuerza ante los manifestantes" = "the police made a show of force in front of the demonstrators".
Esta es una manifestación: http://www.elpais.com/comunes/2003/resumen2003/tema_01c/1.jpg
In English, we call those "demonstrations" sometimes.
I have often seen the word "manifestaciones" for "demonstratons" or "protests" see this: http://www.huffingtonpost.es/amparo-rubiales/el-marzo-de-las-mujeres_a_22010515/?utm_hp_ref=es-politica
"Protestar" es el verbo. Tambien "manifestar" http://www.informador.com.mx/mexico/2017/706089/6/graue-confirma-presencia-de-unam-en-marcha-contra-trump.htm
Why is 'protest' a valid choice? Not all demonstrations/manifestations are protests, right? When people went on May 1 demonstration in former USSR (here in the States we call those events 'parades'), they weren't protesting anything, but rather simply expressing their solidarity with other workers.
Can someone please enlighten me?