I found Android's TTS too "robotic" and low-quality lately and thus tried a few alternative engines. (Samsung's has always been my favorite, but, infuriatingly, they don't allow its usage in third-party-apps any longer). After trying out a few free ones, I ended up buying (one-time purchase of 3,99 €) a commercial TTS engine (to be more precise: a specific German voice, "Claudia", of said engine), and am very pleased. Some things are pronounced correctly (e.g. "links halten", see my original post), while others are wrong. But overall, it's easily 300% better (more natural and enjoyable) than Google's German voice, in my opinion. Maybe I'm just particularly picky, regarding this - after all, Android's TTS works great and is free.