One mystery is why the northern boundary of Easttown is not a straight line. In the purchase by The tracts on the Tredyffrin side of the boundary were patented at various times. The 4 tracts abutting Easttown were patented (going from west to east):

Henry Wright (1682) and John Hort (1685) - overlapping patents
Owen Roberts (1714)
Thomas and Cadwallader Jones (c. 1702)
William Standly (1685)

So the only Tredyffrin tract that could have impacted the laying out of the Easttown tracts was that of Henry Wright but that would not have impacted the laying out of the Wood-Shardlow tract.