Synthesized answer
The provided passages do not contain information about what questions remain unanswered in the book "On Lisp."
The passages do mention that "On Lisp" is known for its complete description of Common Lisp macros and their uses, and that it covers other aspects of bottom-up programming in Common Lisp [Passage 1]. They also explain the concept of solving programming problems by building a specific language using Lisp macros [Passage 1]. However, there is no mention of any unresolved questions or topics that the book leaves unanswered.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: On LISP by Paul Graham Description: The title itself, "On Lisp", is a reference to the idea that you can solve a programming problem by first building a programming language that lets you talk about your programming problem easier. In Lisp the programmer builds this problem specific language on top of Lisp itself using basic Lisp constructs called "macros". This style of programming is called "bottom-up programming". On Lisp is especially known for the complete description of Common Lisp macros and their uses, but the book also covers many other aspects of bottom-up programming in…