Required information:

1. 1.19.2 (probably applies to any)
2. any
   To reproduce:
   Edit assets/enchanting-system-overhaul/textures/gui/ench_buttons, more precicely, the third box (pink one)
   I expect it to render as the rest, with changed textures
   Expectations :
   
   Reality :
   

After looking at the code for only a tiny bit, my conclusion is that this seems to be caused by the EnchantmentListWidget.java file registrering the scrollbar as a fill instead of some blit magic
Im no expert, but i hope my guess helps.

My hope is to be able to "vanilla-ify" the gui of this really cool mod.
Perhaps in the end proving a resource pack that would achieve that within the mod could be a solution ??
Thank you for reading

ah yes fixing that was planned probably in next release

Font, scroll menu background and slider colors can now be customized via json files. For examples refer to this package