In the article above, the intention appears to have been to indicate that not all the main subject's assets, had been disclosed.
What we get instead is:
"...there could be some assets that have not been undisclosed."This has the opposite effect of suggesting the said 'some assets' have been disclosed, which obviously contradicts the import of asserting that 'court documents also make no mention of any bank accounts'.
Does that make any sense to you?
Certainly not to me!