I can finally clearly see and understand the issue, and yeah you might be right, and it could be the same or related issues. But at the time I did not understand the issues nor was it possible for me to see/ reproduce it.
Anyway, I have shared this with our 2nd tier and will update you when I have some news.
we have checked this specific case, and it seems there is no easy workaround at this time. Our devs will check it out further and try to fix it in future versions, but this will take time.
In the meantime, the best workaround we can suggest would be:
1) For the wp_navigation - you have to translate it, and then adjust it with correct translated IDs in the DB.
2) For the page, you can edit it via Gutenberg by switching to "Code" view in the backend and specifying the translated "ref" value. Which is your (translated) navigation menu template, you can check and translate these from WPML > Translation Management also. Also, make sure to manually select the correct translated parent page.
Video: hidden link
I will update you when I have some news, but note this will take some time.