I applied the following patch eventually:
{{{{{{{{{ ((pair? x) - (map (lambda (x) (ac-qq1 level x env)) x)) + (let ((t (lambda (f) (ac-qq1 level (f x) env)))) + (cons (t car) (t cdr)))) }}}}}}}}}
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like this
I normally use "{{{" and "<<<<" as delimiteres in a plaintext . But obviously it doesn't work very well here, so I'll keep in mind to use indentation instead.
Thanks again.