Off by one error
I keep thinking Grace Chapel was born around 1771, because she died in 1840 age 69, but she died early in 1840 — 30 January. (Hm, 175 years ago yesterday.) Chances are her birthday was later in the year, in which case she would have turned 70, so was born in 1770. If the information is accurate.
If she was born between 31 Jan and 31 May, then she would have been 60 on census day 1830 — meaning she could have been the 60 to 69 year old female in Jabez’s household, without being entered in the wrong column.
(There’s still the 10 to 14 year old male. Can’t explain him so easily without resorting to enumerator error.)
I’ve fixed up Grace’s estimated birthdate on three pages on this site. Hopefully not too many other places to correct…