Multisig is NOT fault tolerant:

In a 2 of 3 multisig wallet (for example), to sign a transaction, you need 2 of the 3 private keys, but ALL 3 PUBLIC KEYS.

If you loose one of the 3 seed phrases and haven’t backed up the XPUB’s, you won't be able to reconstruct your wallet if you need to.

You will therefore loose access to your funds.