Glad that you appreciated my research :O)
I am not Geir Moen my secondname is Eide.
I came across an elder bygdebook for this area published in 1924 by Arne Stuland. In this book Hans son Hans b 1777 is not mentioned. I assume the source to Karis age is the probates after her parents .Her fathers probate is dated 6.Th August 1801. her age is then 20 ys. her mothers probate is dated 12 th February 1790 Kari is then listed as 9 ys (difficult to read may be 91/2 I would rely more to her mothers probate. Her sister Mari is f.ex listed as 1 3/4 ys.
Her mothers probate it starts mid 2nd column left page.http://arkivverket.no/URN:sk_read/24038/5/