I have copies of the Logan County KY tax records the have Onecypheros (with his various spellings) there in the 1790's through 1809. He is in the 1810 Butler County KY census (apparently a change of county lines and nit nessicarily a move). There are other Standlee's but I havent done enough research to confirm the relationships.
I have read the CCHQ story on the settlement of Arkansas by John Benedict and 3 sons of john Standlee. The story was originally authored by John Benedict's son. I can send a copy if you haven't yet read this.
In the story it mentions the devastation the Benedict Family suffered due to the New Madrid Earthquake. (more on this later) it states he moved his family in with his father in law, and then set out for a part of AR explored by John Standlee years earlier. John Benedict and the Standlee's are gone a couple of years going to the designated spot near the Cadron river, clearing the land and setting up homes. They then return for John Standlee who makes that spot his home. John dies there in 1820 and is buried nearby. My recall is fuzzy but the name of where he is buried is something along the lines of Palmyra, though that isn't quite it.
That would explain why you Lise John in 1820. His wife Sarah lives with the Benedict family a number of years, with her daughter Rebecca and the author of the story.
Back to the earthquake. From other readings the major shocks of the Earhquake began in Dec 1811 with big quakes in Jan 1820 and continuing through to Mar. 1820. I was googling with search words of new Madrid earthquake John Benedict Missouri and Arkansas, one of the hits supplied the detail of the city the moved from, that is, where they were living during the quake and before the subsequent exploration of AR. I have that in my notes somewhere if you need it.Gosh the more I think about it I'm not remembering if the article states whee they were at the time of the quake, or at the time they set out for AR. It does seem to me that Onecypheros was separated rom his father at about that time. But with more effort in piecing together the time and place of his childrens births and marriages a time line perhaps could be created. That's really an area I loom forward to exploring more. (I've only been at this since last June).
I hope somewhere in there you found something you didn't have before.