But for lisp, a more complex solution is needed. It's easy for a human lisp programmer to keep track of which closing parentheses corresponds to which opening parentheses because the editor highlights parentheses pairs as they are typed. How can we give an LLM that kind of feedback as it generates code?

That's a different question than the one you asked. Are you saying LLMs are generating invalid LISP due to paren mismatching?

That's what the comment I was originally replying to was saying.

If the LLM is intelligent, why can’t it figure out on its own that it needs to write a program?

The answer is self-evident.