I know you guys swear up and down that WPA determines spell success on Support spells, but I have been failing consistently with 2.5 mod WPA on Humans with under 1 mod WPA who are almost identical in size and NW, but the only anomaly is that they have a single digit % of Guilds. I succeed comfortably on provinces in similar situations who have double digit Guild %.
You sure there's absolutely no way that Guild% is impacting Support spell success?