[Zonx]

Based on your screenshot, my guess is that a Composit object is getting inserted into the SpellEffects scrollPage, and the PlainTemplate gets repeated inside that.

Use an OnHover script to check what the scrollbar's "Control" property is set to at runtime. That is most likely the mystery object you need to set PackSize on via script. My guess is that the resulting object tree looks like the following

ExamineEffect
|_ SpellEffects (Template)
|_ PlainTemplate (Template)
|_ ScrollTemplate (Template)
... (More templates and window dressing)
|_ SpellEffects (Clone)
   |_ ScrollTemplate (Clone)
   |_ Composit (Mystery Object Vertical layout)
      |_ PlainTemplate (Clone for non-dot description text)
      |_ Composit (Mystery horizontal layout, left padding to indent bullets)
         |_ DotTemplate (Clone)
         |_ PlainTemplate (Clone for dot text)

Oh and use an onHover script for the PlainTemplate with a buncha parent concats to get the actual parent trace.

onhover="
tooltip=Parent.Name
tooltip=Parent.Parent.Name ##.## Tooltip
tooltip=Parent.Parent.Parent.Name ##.## Tooltip
tooltip=Parent.Parent.Parent.Parent.Name ##.## Tooltip
tooltip=Parent.Parent.Parent.Parent.Parent.Name ##.## Tooltip
"

Should produce something like...
root.ExamineEffect.SpellEffects.MysteryObject