会 instead of 能 is better. Both should be accepted.
They are both okay.
Often people say, “我会说” to mean "I can speak," i.e., "I know how to speak." “我会说流利的西班牙语。” You can also say, “我西班牙语能说得流利,” meaning "I can speak Spanish fluently."
我会说流利的西班牙语 should also be accepted.
Is this OK?
This is the response I would have given
This sentence refers to the degree of attainment. 能 is better.