"Ella haría una buena novia."
This spanish sentence means "She would DO a good girlfriend" makes no sense. It should surely be Ella sería/estaría una buena novia..?
It also means "She would MAKE a good girlfriend", which makes sense in English, but I don't know if it makes sense in Spanish. It might translate as "She would make (construct) a good girlfriend", rather than "She would make (be) a good girlfriend".
PS "She would DO a good girlfriend" would make sense in English, but would mean something very, very different from what I believe is intended...maybe she doesn't DO bad girls XD
Interesting that it's 'make' here but in the sentence "¿Harías algo por mí?" DL would only accept 'do' and not 'make".
hacer can mean both "do" and "make", but only in the literal sense.
"Would you make something for me?" ... that seems literal in most contexts, no?
Absolutely. When I said "only in the literal sense", I was referring to the phrase above "she would make a good girlfriend". I still believe you cannot literally translate it to Spanish like that.
However in the phrase you said, definitely. For example if you ask an artist: ¿Harías algo por mí? you can interpret that as: "would you make something for me?". I can imagine that you would then use the word "para" instead of "por", but of that I'm not sure.
I agree, I am pretty sure that a native Spanish speaker would never say, "Ella haría una buena novia" in order to say "She would make a good girlfriend." I am not sure exactly how it would more properly be said, however I think it is sería.