Translation:Can you speak English?
This is what the people on Quora said, that 文 implies culture as well as all facets of the language whereas 英语 is more the spoken language: https://www.quora.com/What-are-the-differences-between-yingwen%EF%BC%88%E8%8B%B1%E6%96%87%EF%BC%89and-yingyu%EF%BC%88%E8%8B%B1%E8%AF%AD%EF%BC%89
"Are you able to speak English?" -- should be accepted. It's both the closer to the Chinese and more common than "Can you speak English?"
会 does not really mean "can or able to" in the phrase "你会说英文吗？“ 会 means to know how to do something. to be able to do something physically is 能.
"Are you able to speak English?" hits the ear weird and is an unlikely sentence to use in conversation ever. This is a contextual translation.
I don't know. As a native speaker, "Are you able to speak English?" is very natural -- It is how I answered it but it was marked wrong.
And one common and natural way to ask a person if he or she has the skills to do something is: "Can you do this calculation?" "Can you understand math?" "Can you speak English?"