It appears they weren't in any way assuring users that the Trump org financial statements were representative of reality. Just that they were put together from unaudited Trump org material to conform, as best as possible but with exceptions, with US rules.
But if the inputs are worthless, so are the outputs, however you apply the rules.
And it sounds like Mazars is now aware that the inputs are worthless.
Having said that, Trump does have a portfolio of valuable properties. Value, like beauty, is in the eye of the beholder, so it would be hard to argue that a valuation is necessarily bogus. For me, the question is, was Trump saying one thing to the tax authorities and another to the banks. Because that is a fraud in both directions. If he did, and he signed docs, he'll go to jail.
Meanwhile, any sensible lender is going to demand the return of its money and/or the property against which it is secured.