Everything is in pixels, Gimp works in pixels. The length of wings (LoW) is the arrow head. Larger the value, larger the arrow head.
There is adjustment to the shape, the angle between arrow and wings is the 'pointy-ness' and Fill head of arrow is 'style'
Same with the stem of the arrow, that is the brush thickness (BT) value. Thickness in pixels.
I do not know how you got your result. I do not know the image size or the script setting.
Another short video that might help. https://youtu.be/6Vb-A5e14ik
In my timezone, time to call it a day. bye.
There is adjustment to the shape, the angle between arrow and wings is the 'pointy-ness' and Fill head of arrow is 'style'
Same with the stem of the arrow, that is the brush thickness (BT) value. Thickness in pixels.
I do not know how you got your result. I do not know the image size or the script setting.
Another short video that might help. https://youtu.be/6Vb-A5e14ik
In my timezone, time to call it a day. bye.