Each of the icon_ files has an attribute on the outer <Page> tag with a name of "1location" (except icons_world.xml which has "1Location"). This is not legal XML as attributes cannot start with a number.
The file icons_qey_adv03_caves_0.xml has IconStyle="Skinnable_Styles.POI.NAME'" with a spurious ' at the end. I assume this is just a typo.