When you click delete, Special:PageTranslationDeletePage opens and says Deleting translatable page "xxx" and lists all the pages it wants to delete:
List of pages to delete
xxx

Translation pages
Translation unit pages
Other subpages

In total 1 page to delete.

you click "do the deletion" and a page opens that says:
Deleting translatable page "xxx"
Please check the page translation log for errors and completion message.

But I can't see any messages on the page translation log.

After you have done all the above the page "xxx" is still there, but now the "Mark this page for translation" link has disappeared from the top of page. Now when you click delete, a normal delete interface opens instead of the Special:PageTranslationDeletePage.

IMO if a page was never marked for translation it should always open the normal delete interface, not the Special:PageTranslationDeletePage.