There is an interesting line that one must draw, in my opinion, between the tamperment of an archaeological site and the rescue of deteriorating artifacts. It seems to me that there isn't much of a difference between digging up shrapnel in Karelia and taking bits of brick from Obersalzberg. The only practical argument I can think of is the fact that relics in Karelia are likely to rot away otherwise, while the ruins of the structures in Obersalzberg have been discovered, and should remain as entirely intact as possible, so that future generations can enjoy them. With too many people doing things like what you did, the site will soon be lost.
In any case, when one removes an artifact from its site and therefore its context, it becomes irrelevant. In one photo I see the ruins of a structure in Obersalzberg. In another, I see rocks. Same material, different context.
My advice to you would be to leave things be from now on, for both legal and ethical reasons.