Reach has been clarified and should read as follows:
Reach (X): Melee Attacks can be made at Range (X). They are still considered Melee Attacks. During an attack, the spaces directly orthogonally or diagonally that a figure can Attack through with Reach may be counted for the purposes of Flanking. This Flanking benefit only applies to the figure using Reach to count these spaces.
E.G: In the diagram below Zeke has a weapon with Reach. Since Zeke is directly 1 space away from a position in which he could normally Flank, he will gain the Flanking bonus. However, regardless Nightingale could not. If Zeke were one space north or south of this position he could not gain the Flanking bonus.