The more proper translation is "What has been happening?". "What has happened?" is the translation for "O que aconteceu?". The questions are aaalmost the same, but slightly different.
"What has happened?" is a good question for someone that is hurt, maybe the person fell out of window or something.
"What has been happening?" is a good question for someone that are in an strange mood, maybe not sleeping well recently. Get the idea?
What has happened? Action is concluded. Whatever took place may impact the present.
What has been happening? Action may still be in progress or has ended a short time ago and its effects are still in evidence.
Native speakers tend to choose the progressive form over the non-progressive when there is little difference in what is being communicated.
The "pretérito perfeito composto" always translates into the "present perfect progressive" when active verbs are used. It involves repetition and is associated with adverbials (either explicit or implied) like ultimamente, recentemente, os últimos meses, etc.
The "simple present perfect" translates to several tenses in Portuguese depending on context.
i believe "what has happened" would be "que tem acontecido" just as it would be "que ha pasado/sucedido/ocurrido" in spanish. on the other hand, "what happened" would be "que pasó/ocurrió/sucedió" just as it would be "o que aconteceu" in portuguese... i mean, being both almost the same, seems legit
This is a complicated issue. First thing to understand is that portuguese and english have different structures. And likely you have a third mother tongue! For example my language has just a single past tense. Some tense in language A could express the some of the ideas of a tense in language B, but many times to express the same thing, just choosing a tense is not enough, you need to add more context. I think you can't spare reading grammar here. Duo will let you practice. (But as we know too well, Duo is often not perfect either.)
In informal speech, there really isn't much difference between "what happened" and "what has happened". (Both refer to a concluded event.)
"What has been happening" can either indicate that that the action is still ongoing or that it ended a short time ago with the effects of what took place still in evidence.