In frontend development, it's pretty common to use German to stress test UIs, as it's a commonly used language with a lot of long words. It reveals all sorts of UI issues - text that doesn't wrap properly, buttons that are pushed off the screen, etc.
I don't know German, but I do like the idea of using compound nouns rather than inventing new words.
It's also common to test UIs with Arabic, to test handling of right-to-left languages. At work we have a "fake RTL" language that's English but rendered RTL. It's interesting because everything is flipped - for example, a left-hand sidebar is instead on the right side in RTL languages. Company logo is at top right instead of top left.
Because I used Arabic as an example rather than Hebrew? Or because I'm unfamiliar with RTL languages?
In any case, it's pretty easy to figure out that I'm Aussie :)