I understand that scripted document are ones containing script elements "and/or HTML forms", according to [1]. However, epubcheck seems to ignore the <form> element when checking the correct use of scripted.

On the other hand, the rest of the spec seems to use the word "scripted" only for actual scripts, not forms, so the issue is not entirely clear to me. Could it be a spec problem? The 3.3 draft is clearer about this [2].

[1] https://www.w3.org/publishing/epub3/epub-packages.html#scripted
[2] https://www.w3.org/TR/epub-33/#sec-scripted-content