I know this is really old but in case anyone else falls upon this question.....
This probably would be a great question for those researching Kentucky. The history of the area is probably important here. Now keep in mind that my memory of history here may be entirely wrong, but you can check on it to be sure.
If memory serves me correctly, settlers in Kentucky were illegal under British rule and the Revolution wasn't over until 1783. This would mean that prior to the end of the war, Kentucky had to make their own government in their own way. Kentucky didn't become part of the US until the 1790s, I don't think so they still were running it their way.
My best guess is that the townkeeper was either a guard (this was Indian territory from a legal standpoint) or a mayor of sorts. I found a federal proposal for a change in law here:
https://www.govtrack.us/congress/votes/6-1/s31It mentions townkeepers too. My best advice if you want to be certain is to look into local laws (though they were laws from Kentucky, not the US) at that time and see if anything pops up. Perhaps even local papers too, if you can find any or have access to them. Most of the laws or rules though, should be online and readily available at their gov website and archives website.
If you find out, please post back. I'd love to hear the outcome on this. Good luck!