I don’t think that’s Spanish. Nahuatl, which is an indigenous language spoken in Mexico, does use x- to transcribe the sound commonly written as sh- in English, so that’s probably a Nahuatl place-name.
In the case of Xitter, though, the reference is generally to Mandarin Chinese, which uses x- to transcribe one of the two or three distinct sounds in that language that all sound like sh- to Anglophones.