Messages translation issue

https://prnt.sc/opiwaz
Hello, we have website in German. So I installed DE lang pack for plugin, all messages are translated in DE. But some of them like
– Only letters and spaces are allowed
– Only numbers are allowed!
are still in ENG, and i cant translate them cause they are not in messages list in from settings
Pls help with this

The page I need help with: [log in to see the link]