Perhaps another route you might try is
In the area of llanrhaeadr ym Mochnant, montgomeryshire,
There is on the 1861 census a district of Llanrhaeadr called Henfache. Lots of people on my tree live in that area and within Henfache on page 4 of 11 there is an area
where they have houses down as Commins, I believe it may have been at one time Common Land ?/
Certainly in 1861 there are various residences there.
It may be late for your relative b 1786 but this could be checked on the 1841 census.
sometimes Henfache is down as a place on its own and other times it is down as a district of Llanrhaeadr ym Mochnant.
Because it is so close to what is written down on your ancestor's document I just thought it may be worth looking into??