Thanks a lot saulgoode!
Works perfectly! Just needed to change FG-BG-RGB-MODE to FG-TRANSPARENT-MODE for multiple fills on one mask.
Just as a side note, I kept working on my original thoughts and it works (with help from your script), however your method is far more efficient in every way. I'll just post my script as reference.
(width (car (gimp-image-width image)))
(height (car (gimp-image-height image)))
(set! x1 (* 0.5 width))
(set! y1 (* 0.5 height))
(set! x2 (* 0.05 width))
(set! y2 (* 0.5 height))
(gimp-edit-blend alphaMask FG-TRANSPARENT-MODE NORMAL-MODE GRADIENT-RADIAL 100 0 REPEAT-NONE FALSE TRUE 3 0.2 TRUE x1 y1 x2 y2)
Tag: x y coordinates multiple several radial gradient fill open image percent percentage percentages