The language spoken... I mean whistled today is the Silbo Gomero, which is indeed centuries older than ME as it is a whistled version of spanish, and we spaniards didn't set foot in the Canary Islands until the XVI century. But it is an adaptation of whistled Guanche, the native language of the islands, probably a Berber language and now a dead language, but not then.
Guanche is supossed to had been simpler than spanish, allowing an easier translation into whistling: whistlers apparently use just about two vowels and four consonants (there seems to be some linguists arguing about that for around 50 years now). Anyway I guess you could adapt hermetic magic to it, as some hermetic magi already use other languages than latin to cast magic. The only issue that I see for an hermetic integration is that it already requires gestures to modify the sounds in the whistle, which probably won't mix well with the already existing spellcasting gestures.
Not certain about the others, but by 1220, Turkish kuş dili already existed in some form (mostly around the Black Sea rim of Anatolia) - granted it was then a whistled form of Old Anatolian Turkish, not Modern Turkish, but at least it's contemporary in the period.