I am a non-EU citizen who lived for a few years in Germany and left it a few years ago. My German landlord didn't pay my deposit back. When I contacted him by email about that, he responded by email that he had used my deposit to make small repairs, paint the apartment, etc. He added that my deposit wasn't enough to cover the expenses and that he would send me the bill shortly. But he never did, and it looked like his actual expenses were considerably less than the deposit. However, because I had already left Germany and was living in a different part of the world, I decided not to bother suing him.
It has recently come to my mind that he may have dishonestly filed a legal case against me in Germany to claim the alleged difference between my deposit and his expenses to repair the apartment, in the hope that I would not learn about the case and will thus be obligated to pay him if I ever come back to Germany. He knew I was departing Germany. A complicating factor is that I forgot to deregister (i.e., abmelden) when I left Germany. This means that if he filed a case against me, an official notification letter may have been sent by the court to my registration address, which is the address of that apartment, so I may be considered notified about the case despite having left Germany.
My question: How can I find whether he filed a legal case against me? Is there any online database, or where can I request the information? I live outside the EU.