However you decide to translate the format, you will want to have a good description of the format, which is provided by a grammar. Once you have a grammar, converting into a format suitable for P::RD should be fairly straightforward.

From your example format, a coarse version of the grammar would be something like

<page> :=   /page p\d+ \{/ <question>* /\}/
<question> := /question \w+ {/ <label> <choices> /\}/
<label> := /label \{ [^}]+ \}/ 
<choices> := /single {/ <choice>+ /\}/
<choice> := /\d+ (Yes|No)/
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where I have not included whitespace elements in the regexes.

Here the nesting, or hierarchy is represented by different grammar elements contained inside others.