How do I edit wrong statistics for words not at target language?

I imported an ebook in French and only the introduction is in English, I just quickly skipped through the text to go to the French part, but if I click the gray arrow, all the text is counted as new French known words, which shouldn’t be allowed and the system should be able to identify them as not being French (unless the spelling is the same) and hundreds of words were added. Is it possible to edit the data statistics and exclude the “alien” English vocabulary added?

You can’t remove them from the Known words stats all at once, but you can click on each word in a lesson and ignore it, that will remove them from Known words stats.
in future, if lesson has English introduction, I suggest you to open it in Edit Lesson and remove that part.