Family Historian User Group

What I would like to do is search all named lists for an individual. In other words, if I have John Doe in multiple named lists, I am hoping to return a list of those named lists.

I have read of, and used, the IsInList() function and it works beautifully to tell me is an individual is in one list, or everyone in a specific named list. I have not found out if it is possible to loop through all named lists. I have been plugging away at the KB articles so if such a facility exists, can someone please point it out to me. I have also looked through the KB downloads for a query but none seem to fits. I have not viewed all of the plugins yet, so if the functionality exists in a plugin, I am ok with that too.

It is not possible to 'loop though' anything in a Query. Only Plugins can perform that kind of searching.
Unfortunately, there is no easy mechanism in Plugins to find the names of Named Lists.
The best you can do is have a Query Column for each specific Named List using the =IsInList() function.

Since the named lists are stored in a .fhss file inside of the Snapshots folder under the project name and they all start with '1 _Lists', I think they could be extracted in a Lua script (if I knew Lua and this may be a reason to learn). Do you think there would be any known issues opening and reading this file? You have the plugin development experience that I lack, so you may know that the file can't be opened or accessed, if so, then I won't spend any time working on it right now.

Yes, that is one of the sort of less than easy techniques.
Bear in mind that those Snapshot files are copies of the GEDCOM file.
So to get the current latest set of Named Lists you can use the Project's GEDCOM file.

Use the strContents = fhLoadTextFile(strFilePath) function to load the the GEDCOM file into memory.
Then it is possible to find the Named Lists as you suggest.

If you want to start learning Lua and write a plugin then I can help but not this evening.
Start with FHUG Knowledge Base Getting Started Writing Plugins and try some of the tutorials.