Hi, can you explain what you mean by securing 6 elements for a 2 of 3 multisig? What does it mean that I can lose 4 elements of it? What when I lose 2 seed phrases? Doesn't make sense to me.
What do you mean by key? Why do I need the wallet config file when I have all seed phrases? You should also be more specific in the Fault tolerance chapter. What if I do not have the public keys but lose everything but 2 seed phrases? Now I cannot recover my wallet.
In my understanding, you have 3 seed phrases and 3 pub keys that were derived from the seed phrases. A multisig wallet can be restored when
  • all 3 seed phrases are there
  • 2 of 3 seed phrases and 3 pub keys are there
  • When I use HWW, it is likely that the pub keys are stored in the HWW, now I can restore when I have 1 seed phrase and 1 HWW left (from a different seed phrase)
You should read our article comparing 2-of-3 multisig with 3-of-5 multisig, which goes deeper on all the questions and scenarios you're asking about: https://unchained.com/blog/bitcoin-multisig-2-of-3-vs-3-of-5/
but to briefly answer your questions: you need to secure 6 elements for standard 2-of-3 because we assume you should always have a hardware wallet and a seed phrase backup.
the 4 items you could lose are: 3 hardware wallets and 1 seed phrase. That would leave you with 2 seed phrases.
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I was confused about securing 6 elements for the 2 of 3 multisig, as a seed phrase is also a key. The link you send me make more sense to me. Thanks.