I just listened to the rock one, given that I don’t speak German nor have any interest in ‘making ofs.’ 
The song flows well and sounds good, although it’s not really my thing. 2:26 section is my only criticism, the keyboard is just too dull, both musically and in the sound/dynamic level. The odd super fast scale run or arpeggio can make all the difference used sparingly, although I understand that not all performers are capable of actually playing anything remotely virtuosic. Maybe it was more of a producers decision, but it’s an upbeat song and this section isn’t like taking it down a notch, it’s still upbeat but missing that burst of energy from an instrument. Other than that I thought it was performed, recorded, mixed and mastered very well. I can’t fault it in that regard, sounds like any other record you’d buy at the music store so well done.