A PJ inconsistency?

Yes, Novlamothian, that is exactly my point, and even emphasises what I stated, though I hadn't even seen that as proof until you pointed it out. The inscription on the door is, in fact, Sindarin, the grey-elvish language, which was the commonly used elvish tongue. This disputes any idea that it was some "other" form of elvish foreign to Frodo. A minor oops on PJ's part, just not thinking through it thoroughly enough before changing who gives the line. Another case of trying to change something, and finding out that Tolkien had it right to begin with, but this one they didn't catch. oh well.