1. It can well be said that singing ‘adamah veshamayim…’ today has become a Minhag Yisrael and gets that special halachic status, which would mean that it is automatically valid as long as there is ANY legitimate backing for it
Uh, I don’t know how minhag yisroel works. But with that logic, you are saying if enough people do something it’s muttar. So we can make it muttar to do biluy arayos if it’s common? Cuz I think avodah zara and giluy arayos are on the same level, the whole die before you do it type.