Synthesized answer
The provided passages do not contain information about unanswered questions within "Glass I & II." The only passage available is a title page for "The Art of Glass by Antonio Neri" which includes the page count [Passage 1]. Therefore, it is not possible to determine what questions remain unanswered based on this limited information.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: The Art of Glass by Antonio Neri Pages: 436