I found my father's letters from his sisters and brother and nephew in Germany. All are in German, and most are in a spidery old style handwriting that is unreadable by us moderns. I have no German, so the chance that I can decipher anything at all is too slim to mention.
I did have a friend who speaks German well look at some of them, and he struggled but got little out of them. I have resorted to creating a catalog and sorting by year and combining with pictures from the same year, but I guess that the content may well remain a mystery. It is sad in a way, especially since they were written to the US from Germany in the late 20's through the 60's and might have some interesting stories to tell.
That said, they may also be dull as dishwater, but they make for interesting photos..