German made doesn't mean anything, nor does american or English when it comes to measuring tools. If they're relatively inexpensive, they're just a production item and not something like a machinist's tool.
It's hard to figure out what's square and what's not without having one true square (which can be checked off of someone else's true square so that any given person's "one true" square is just an inexpensive used engineer's square that checks out fine).
In the US, there's a gaggle of measuring tools stated to be made here - some are aluminum and large and "guaranteed" and some are starrett lookalikes at a relatively low cost with soft heads, soft parts and soft rules (they're sometimes square but other times really hard to work). A friend here bought a starrett certified square and a $100+ "guaranteed" 12 inch square made of aluminum to use for woodworking - the latter wasn't close to square and he didn't know it until he bought a certified square. The "guaranteed" square was out enough (some fraction of a mm) that it was causing him problems setting his jointer fence, etc. He just didn't know what the origin of the problem was and blamed the tools and not the square.
Check the guarantees on tools, too - they're often different than they appear. e.g., trend warrants a flatness amount per inch on their diamond hones. It's a pointless number because it can generate an entire diamond hone out of flat enough (but still in spec) to scuff the outside edges of an iron and make it convex in the face. Tons of straight edges and squares are also guaranteed by the inch, and almost as expensive here as something like a basic starrett version that's got a guarantee 10-20x tighter.
Forum advice on this stuff is bad. "nobody needs a square that square for woodworking". That's fine and good, but you'll eventually need a square that's actually square for tool setup, making tools or checking something.
