For what it's worth I can share my experience. I was admitted to a decent PhD in NT this round of applications. While I have formal training in the ancient languages, I'm self-taught in German. I put that on my CV, and in the interview explained what I did and how I intended to sharpen my modern languages in the time between now and the beginning of the program.
In short, I'd imagine that most would be reasonable, and care more about the fact that you can read the language than that you have credits to prove it. A certificate or some sort of documentation never hurts, though
