Can I get sued later for buying assets from a company that was already going under?

It's possible, particularly if you bought directly from a struggling owner outside any formal, court-supervised process. If the company later ends up in a formal insolvency proceeding, a trustee, receiver, or unpaid creditor can potentially challenge the sale as an improper preference or a transfer at undervalue, especially if the price looks low, the buyer had some relationship with the seller, or the buyer knew the seller was in serious financial difficulty at the time.

Being sued personally is less about who you are and more about whether the transaction itself can be shown to be unfair to the seller's creditors. A sale conducted through a court-approved process, with the price and terms scrutinized and approved in advance, carries much less of this risk, because the court has already effectively blessed the transaction. If you're buying directly from a business you know is struggling, solid due diligence, a fair, defensible price, and good records showing the deal was conducted at arm's length all reduce your exposure to a later challenge.