I rotated my map backwords, Ioaded it in Radiant and flipped every brush on the X axis so now its technically "reversed" from what it used to be.

So now I wonder, only the brushes are flipped, but when I select any xmodels or prefabs, and flip it the same way I did to my map, the xmodel, prefabs are all messed up now.

I selected everything in my map, flipped it on x axis and only the terrain, any brushes that are not in a prefab flips. But if I flip and xmodels or prefabs are selected, it doesnt go along with the flipped terrian, its turned upside down or all messed up.

Is there a way to make the xmodels sync with the brushes so I don't have to re-model (literally) the whole map again?

try this simple trick...save ur map, start a new map then import ur map inside this new .map file; this would mean ur whole map is now a prefab. u can now rotate everything as it is. try that. save ur new .map and watnot and use ur old files as the new ones with the new's .map name. just saying.

Nope, doesnt work :( a prefab or xmodel doesnt flip on x axis hmm.

You have to import everything from the prefabs, not the prefab itself! (Turn everything into script_brushmodel) Also the models should be script_model wich than requires some clips ;)