Caltrain purchased from Mitsui one test locomotive, ex-Amtrak #938. They also purchased #929 for parts to get #938 running. (My source for this information is Caltrain’s contract with Mitsui.) Amtrak did the refurbishment. I imagine that a cross-country move of such an unusual vehicle would get some attention, so it might not have happened yet. Every ACS-64 out of Sacramento can be tracked east, so an AEM-7 headed west will surely be on the railfan radar.