seller disclosure does not apply for more than 4 units

either the buyer (you) exits the contract and lose the deposit and hoping the seller does not sue you for executing the contract( they have rights to do so but i doubt it if you write down your reasons for backing out ).

or get contractors asap to do estimates on the repair cost ( it won't look like small one when it's coming to foundation work ) and keep the deal, after all you still have 9 more years before you face the problem.

not enough due-diligence work upfront and never ever sign an non-contingency contract.