Are you testing with exactly that same effect?
To me it basically just looks like you'd have to mark the caster as neutral since a PC caster is marked "friend".
EDIT: here is v0.5 which fixes the excessive "effect already exists" chat messages.
Now it only posts when entering/exiting an aura.
Download:
https://github.com/bmos/FG-Aura-Effe...eases/tag/v0.5

