I'm in the exact same boat as you! I studied Spanish for 8 years and fully considered myself fluent and able to translate scholarly material (as I was in AP Spanish Literature and we did have to read some articles, albeit not scientific ones) but listed Spanish as a language I was comfortable translating scholarly material in. Now if they meant scientific research articles, I'm not so confident about that...But if they asked me to translate Great Expectations or East of Eden or a classic novel, I could.
If it comes up in an interview, would it be valid to just honestly say I interpreted the question as being able to translate novels and the like, rather than scientific material?