It’s possible to get an trace from the output of the parser. In all higher order constructors, if the first element is a symbol that will tag the trace output of that ideom. Then to enable parsing use the boolean variable
do-print, that is located in
(logic guile-log parser). If that variable is true then you will get a parse trace of the parser. To note is that parsing is both traced at success and when the logic leaves that state in e.g. backtracking.