Maxperson
Morkus from Orkus
But irrelevant to the language using it. Call it a language or not, it's still usable by anyone of any language.What you are calling a "mystical syllable" (bu) is a "morpheme". It is a language. This morpheme would be meaningful information about a specific spell and its effect.
Yes there is, because it's the same in all languages. This is D&D fact. It may not be real world fact, but it is D&D fact or else casters could not recognize spellcasting, especially verbal only. Yet they can and RAW backs it up in the verbal components section of the PHB.But there is no language − including no morpheme such as a mystical syllable "bu" − that all casters would recognize and understand.