"We talked about many topics."
Translation:Hablamos sobre muchos temas.
"Hablábamos sobre muchos temas" should be accepted as well. Without any context the indefinodo is as good as the imperfecto.
Any other opinions on this? I reported it
I think the imperfecto would be more applicable to a sentence like "we used to talk about many topics", or "we were talking about many topics, when x happened".
My opinion on the sentence "We talked about many topics" is a completed action in the past, so the pretérito (o indefinido) is the correct tense.
Happy to hear other's thoughts though.
A number of words from Greek brought their (masculine) gender with them. These often end in -ma. Such as tema, programa, problema. But very exceptional. El día is another one but usually you are right to assume -a sugggests feminine.