Multilingual sitemap without translated slug

[AIC-BV]

Hello

I was wondering the following:
What if you have a blogpost, which is NOT translated?

Currently, it will add an URL to the sitemap like https://www.wintercms.com/fr/blog/my-first-post because my-first-post is the slug in the default language.

This page, will display the default language (EN) content.
As far as I know, displaying EN content on a FR page is bad. (and duplicate content?)

Which makes me wonder if slug is NOT translated, the url should NOT be in the sitemap.xml?
If the post is NOT translated, it is not intended for use in that langauge?
But then again, if slug is /garage, and its the same slug in FR, if someone doesn't translate it, then the page won't show in sitemap?

What do you guys think?

--
In my specific case I have a job posting in Dutch.
We only want people that know the Dutch language to apply for it.
So this specific job posting is not translated and is shown a message like this post is not available in your language and has robots='noindex'
The job posting does not show up in the list of blogposts (because only translated posts are shown), but it you use the translation menu from the Dutch page to FR/EN page they will get that message.
This made me stumble upon the issue that this URL is in the sitemap, but my HTML says robots='noindex' which is contradicting the sitemap.xml