Hi, Page Up and Page Down are default RPG Maker controls to move through an entire page in a selectable list. Do you have to have those be the scroll keys? I can disable those from working in the encyclopedia scene, but it might be odd for players who are used to controlling the windows that way in other scenes.
If you want to disable Page Up and Page Down from scrolling the list window, you can add the js to the bottom of the plugin file (basically it makes those keys do nothing when pressed):
CGMZ_Window_EncyclopediaList.prototype.cursorPagedown = function() {
};
CGMZ_Window_EncyclopediaList.prototype.cursorPageup = function() {
};