Have you got a reasonably reliable birth year for Leonora? I see on the 1841 census her age is given as 65, so allowing for rounding, she could be between 65 and 69. As the census was taken on 6th June 1841, this gives a birthdate between 7th June 1771 and 6th June 1776.
I cannot find her on 1851 census, so presumably she has died, but have been unable to find a death registration for her.
Looking at Hethersett baptism transcriptions on Freereg, there is one for a Livah (sic) Reynolds (female child) on 17th July 1771, which would fit the timespan, assuming this baby was baptised fairly soon after birth. Bit of a long shot but it could be bad, faded handwriting on the original and that was the best the transcriber could do. The parents of Livah are Thomas and Hannah. So not the sister of Jane and Metyer (grocer). Mary Reynolds nee Peters was buried in 1802 and was described as widow of Thomas, so he predeceased her. So Thomas cannot have married again and Hannah be his second wife. It is possible the name Hannah is just a mistake, on one of the two transcripts of Metyer's baptism (the one who died young) it says Mary was crossed out and Frances inserted. There is a marriage for Thomas on 8 May 1770 in Norwich to Frances Kiddal/ Kiddele - probably the one referred to as "Kettle", so feasible for Livah to be their child. Mary was 80 when she died so born abt 1722, so a bit old to give birth in 1771.
James Postens pops up again in Hethersett. He is a witness at the marriage of Hannah Reynolds and John Brown on 28 Sep 1775. Hannah is a spinster, so can't be mother of Livah and widowed between 1771 and 1775.