Excluded urls only for specific language

Need more information about the use case. Why can't this be solved with the "Excluded languages" setting?

Hi @walkingdexter,
By selecting Excluded languages ​​settings, all urls as well as alternate urls are deleted.

In our use, the French language is main and we have pages translated into English and it is not possible to have English pages alone.
Our client therefore asked us to keep the alternate urls for the links with the translated pages but does not wish to keep the urls of the English pages.

Thanks for the clarification. This seems to be a very specific use case. If I understand correctly, the problem can be solved with a few lines of code using hook_simple_sitemap_links_alter(). Is this true?