Again, thank you for the responses. Just to clarify, as I originally stated, this is not our native language at all.
Also, NOT Chinese or Spanish even though I think it is still impressive for a U.S.-raised native speaker of those languages to do well on an AP exam. The written section is very involved and difficult.
We speak English and another non-Romance language. Kid took AP exam in a Romance language. I do have H.S. level knowledge of language.
I like the idea of having something in the essays that underscores how this is not their native language. Even going by this thread, it seems like people will assume it is.
DC will look into continuing 3rd (really 4th) language with classes to be on the safe side.
The requirement to graduate is only 1 year of FL classes for this high school. For admission to most universities, students are required to have at least 2 years FL on their high school transcript.