after that create a translation for every page (not a real translation, a blank site, with title and slug)
If this is done, change the url / redirect of the translation page to the other domain (with this plugin for example: https://de.www.ads-software.com/plugins/page-links-to/ )
Thats maybe not the best solution, but im unsure how to fix that else, because you have different site slugs/categories
EDIT:
or u create a custom meta field, a url field.
Where u enter the translation link, for each site.
Edit ur language selector that u change the url with that Custom meta field input.