I did a search, but couldn't find many details about how the keys are going to be splitted, so it's difficult to say without knowing more details.
I can only guess that they are going to use a 3-of-5 multi-signature wallet rather than a 2-of-3 to reduce the risk of collusion between the key holders.
I read through the news and you were right it would be a 3-of-5 multi-signature wallet with the keys splitted as follows;
Sygnum holding one key as a co-signer
Borrower also holding one key too
While the remaining keys are held by independent institutional key holder which I assume will be three different institutions.
This actually balances the question but my concern is that cant the bank ask for signing permission from this key holder institutions and if they can do that then they can simply spend from that wallet without needing the borrowers signature.
