There have been times people have RPed as if XWF is a "real" competition while places like WWE are scripted, so in that sense it would be fine to use such terms in relation to outside companies.

If you start accusing an XWF member of "breaking kayfabe" or other certain terms are used the wrong way against somebody, you risk having them throw it back at you and severely hurting you that week... so my best advice would be to NOT use terms such as those for actual trash taking ammunition against another RPer. For instance, if you were to start saying somebody in XWF is a "horrible face" meaning they're not good at playing their role of being a face, that would be very questionable and you'd be very open for a serious rebuttal from some of the more creative writers. Another example is if you claim people here are running "gimmicks" or not being themselves... that opens you up to huge return fire if the person knows the clever and entertaining ways to defend against that.