To the list of concerns at the top of the BIP, I would add one: losing multisig setup context. E.g. in the event of a fire where you only recover your steel engraved mnemonic(s), but no longer have the wallet descriptors.
Good point.
If you still have all devices and know (or guess) the threshold then BIP48 and sorted_multi descriptors will save you. But if you have a 2-of-3 setup and lost 1 device then without the metadata your coins are lost. In a future with musig(?) and miniscript increasingly the setup data is just as critical as the seeds.
How so? Each signer device should ideally have a copy of the multisig configuration. If you lose 1 device in a 2-of-3, you can still spend from the wallet? Unless I'm missing something here.
I was thinking about a scenario where all devices are destroyed. All you have left are the mnemonics. But indeed if at least one of your devices is still intact AND it has the configuration, you're also good.
But there are plenty of devices out there that can't do this. Those devices can still be useful, even if they can't fully check everything.
Sjors