Wasn't aware that the Germans did barley wines
"The Germans" don't, "some of our craft beer guys" do.
a good (barrel-aged) bock beer would very much meet with my approval.
I know that "good" is always a rather personal point, but Störtebeker (German, of course) had a lovely smoky Mezcal/Gin cask Bock last year. Other than that, I still recommend Kuehn Kunz Rosen - in recent years, they had a Merlot/Dornfelder finished and a St. Kilian finished Doppelbock, of which there are still bottles available in some shops. (Because they're expensive, of course.)
If you like barrel-aged beers per se, the Rare Beer Cellar (or, if you happen to be in London every now and then, the Cask Pub & Kitchen's vintage beer menu) might be worth a look. You'd better ignore the price tags though.