why xmlrules can't manipulate worldspawn or geometries? if it can make triggers, i think that it may be normally to be able to make other things

The geometry is precomputed with the mapping tools and can't by modified "on the fly". The entities are in a separate part taken in account when loading the map, it is why it's easier to modify them with xmlrules.

With the original game, the triggers use a temporary piece of geometry to define their area. But I have added a modification for embedding the area coordinates directly with entities (ex: "mins" "-928 264 -32" "maxs" "-536 424 200"). It is why triggers can be added through xmlrules.