You need to know the purpose of company registration.

Company registrations (Partnership/LLC/Corporation) are used by the owners to shield liability from themselves personally.  So that if they owe money, creditor like you only go after their company assets instead of the personal assets of the owners.  

In return of such protection, the companies are required to publish their formation, i.e. registration, so that everyone is given notice that they are doing business with the company but not its owners.  

Therefore, failing registration requirement, at worst making the company protection weaker, and makes it MORE LIKEY that the owner's personal assets can be pursuit by the creditors like you.  You need not worry that somehow an improperly registered company could AVOID debt collection.   That is against public interests.

You idea of "company" seems still rooted in TV shows and movies.  Learn, learn, and more learning!