Hi Devoted,
I would set up a straight spline for the Cloner Object, so you get the Loop already with a “slider-adjustment”. (Attribute Manager: Object >Rate)
In that way you get a straight line of arrows moving in one direction.
This cloner is then placed under a Null object, so you can place a Spline Wrap as sibling to the Cloner.
The Spline wrap should have a FIX bounding box! (Attribute Manager: Object>Fix Bounding box—checked)
In the Spline Wrap you can set the Spline Size (vs the Size) for the whole spline with a Spline-Interface, so you get the scale over the Spline Path (You named this spline: ArrowRight)
Additional, the ArrowRight.Rail is optional and helps to turn the Arrows on their way into the right direction.
(I have set the Cloner>Transform>Scale value to make the effect more visible, this is not needed!)
Let me know if that works for you. Perhaps subdivide for the final model the arrow, so it bends nicely. I know—this was a sketch only. Thanks for providing it as it makes it easier to communicate.
(I excluded here the Spline Effector—and I think the attached scene speaks for itself.)
All the best
Sassi