Quite simply, UMD doesn't work for scrolls.
Magic up to 3rd Circle is available in Potions, and up to 4th circle in Wands.
This leaves high level magic in the hands of Wizards and Sorcerers, as it should be.
From NWN Wiki (If I'm interpreting it correctly)
The scroll check is actually turned on and off by the local integer X2_SWITCH_ENABLE_UMD_SCROLLS on the module. The standard Hordes handler for the OnModuleLoad event (x2_mod_def_load, and also x3_mod_def_load) checks the game difficulty and sets this local variable appropriately (set to TRUE if the difficulty is at least "hardcore").
Turn off UMD for scrolls
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Turn off UMD for scrolls
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