ok, thanks, I think I'm starting to follow you.
So if I was to create a template file, place all of the symbols that I would need in the document's symbol library, could I populate the drop down with those? From your left example above, could the names of the symbols be populated in the drop down list as those are accessible in script and be chosen and drawn on the artboard on a button click?
If that's the case, couldn't I use wild cards and if statements to feel each separate dialog?
For example-
One dropdown would be linked to symbols whose names began with "Zip*" and the second would be linked to symbols whose names began with "POLY*". These wouldn't be in separate libraries but they would be in the one accessible throught script in the active document.
Is this doable, if not I'll give up and call it a day! 
An AI template file containing all your symbols is fine… That will just be doc.symbols how you chop up that array into sub arrays would be down to you… I don't see how this is going to be any improvement over the symbol scrolling at the bottom of the library palette… See the back & forth arrows in the snapshot… I can jump very quickly between sets of symbols here…
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