You don't need the configuration/descriptor file if you're executing a 2of2 or 3of3.
You just recover the multisig wallet as you would a singlesig, by just uploading the keys to nunchuck or bluewalle...
you proposed multisig as one size fits all which is not so instead i'll stick with singlesig since i'm clearly not familiar with msig just pointing out that everyone should act within their confort zone when it comes to cold storage