I wonder how many mixed Protestant/Catholic marriages in 2018 Germany really care about any of it enough to want to do it in the first place. I suspect any that would bother are probably in their 70s. You have to care enough about it to bother to engage in something that both faiths would generally be against in good faith, but still do it anyway?
Freegards
It just seems so odd to me.
Now if you are in the process of converting maybe I could see it but not under other conditions.