I have created a package of your site and downloaded it to my computer. I'll continue to investigate this issue, and if needed, I will esclate it to our second-tier supporters.
I've found the source of the fatal error and fixed it also on your site. The problem was with the translation of the string "All %s" into German. In German, it was missing the "s". So this is what I did to fix the problem:
1. Go to WPML -> Strings Translation.
2. Search for "All %s" under the "woocommerce" domain with "Exact match" checked.
3. Edit the German translation and add "s" after "Alle %".
4. Click Enter to save the change.
Please see the attached screenshot.
There is no fatal error on your site now.
Can you please confirm that the problem is solved?