Is this a fact, or is this CC folk wisdom? To me, the plain letter reads “four years of a foreign language” - i.e. take one year of FL for every year in high school. For OP, the FL available for him to take his last year is AP French. It seems to me if they wanted to say FL up to level four, they could have just said “FL up to level four” instead of “four years of a FL.” Seems like a better approach is to follow the plain letter (“four years”) rather than trying to rule-lawyer it in your favor and hope for the best.
For kids who are accelerated in math, is it legit to stop after Calc BC junior year, because they’ve taken math up to level four? I doubt it. It says four years of math, and it means it.
Of course, it’s legitimate to say forget Harvard, I want to be happy my senior year. It all depends on what you want.