I do not believe that this James, son of Robert Richardson and Jennet Legerwood, is the Morebattle minister who married Jean KER.
By naming pattern from the children of the Morebattle minister, his father might be expected to be a John and mother Isobel, where there's a handy couple of the right names and about the right age in a John marrying Isobel Pringle.
I have however assumed, dangerous word, that the better candidate for the marriage of James son of Robert & Jennet is the one marrying Elizabeth Lidgerwood in 1760.
The cautioners for that marriage were a William Richardson and James Lidgerwood, and there are a couple of candidates for Elizabeth's birth in the right place - Eckford (but unfortunately, a choice of two, both father James, one in Moorhouse, t'other in Cavertoun.)
5,6