So as MrInterface already wrote, I drove past his home today as I was in the area anyway. Luckily I had his address, as I was the one who send him the STN.
After ringing the doorbell, a voice answered, asking what I wanted. So I asked, if he was the guy, I was looking for (I'm not going to write any names here). Turned out, he was actually his father. I told the man, that his son had something that belonged to me and that I wanted it back (he wouldn't care for the full story, so why bother). He opened the door and called for his son (Circlepit). After a short time, Circlepit showed up, already carrying the two packages (without knowing what I really wanted, but I think, he could guess

He than quickly apologized and said, that he had been on a vacation and asked, if I wanted to have the two packages or if he should send them. I have to say, that he didn't look like if he planned to keep them in the first place and that the whole story could indeed have been a lot of miscommunication and misplanning on his side.
But I still decided to take them with me, just in case. This would of course cause additional shipping costs for me, which is why I asked him, what he thought about that. He than promised to wire me the money, if I send him my bank details, cause he didn't have money on him. I hope, that I will get my money from him.
And that's how I got the Switches back. Here they are lying in my car:

I am currently not at home, but instead trying to enjoy my weekend. I will arrive at home on Tuesday and I can send the packages then, although I might take an extra day to test the Gaming PCB, even though I'm not on the list, I hope you dont mind

As I see it, juho3 is the next in line. If you could send me your address, I can send them to you.