You have to dig deeper, it’s more convoluted than you’d expect (or certainly than I’d expect) 
pfes = FilteredElementCollector(doc).OfClass(ParameterFilterElement).ToElements()
pfe = pfes[0]
elFilter = pfe.GetElementFilter()
filters = elFilter.GetFilters()
filter = filters[0]
rules = filter.GetRules()
rule = rules[0]
ruleString = rule.RuleString
The code is just bare minimum, assuming I’m always interested in the very first element when there’s an array. Just to show the important stuff.
I needed to get this in order, too, so I made this diagram
Btw what Revit version are you using? I’m in 2023 and I don’t see a “Section Type” parameter, only “Family and Type”