- Yardish is now going to be an oral-only language, any ideas what would make
it oral only?
- "If a person with the power of cursed singing recorded a song, could it still have an effect?"
It depends on whether one's intent plays any role in the system of magic you've developed.
In my experience, this is one of the major differences between fictional systems of magic and traditional belief systems. In fiction, the protagonist can unleash an ancient evil/free the princess from her curse/turn into a jackass simply by reciting a magic formula, even without intending to do so, whereas I've never encountered a belief system that works in the same way outside of fiction (although the traditional Palestinian belief that you should never refer to a thing or animal by its name without pointing at it, lest you summon a jinni with the same name, comes close). In fact, according to some systems, the meaning of the words themselves don't matter, only the intent behind the incantation (see, for example, the medieval Christian use of the Hebrew phrase "sisim hemma mulahos usmonim pilagrim uelamos einmispar" from the Song of Songs 6:8 as a charm against worms, even though it has nothing to do with worms and, more importantly, the enchanters who used it had no absolutely no idea what it means, or the extensive use of voces magicae in incantations on both sides of the Mediterranean).
So, in short, according to most traditional systems of belief, a recording is unlikely to produce the same effect (unless perhaps it is intentionally played to do so, like a musical instrument); however, fiction regularly flouts any regard for intent in magic.