Hello Brian:
Having a printer attached to another server is a pretty common situation and shouldn't be in-and-of-itself sufficient to cause printing problems.

• Does the printer driver match the Xerox printer? The Xerox site shows drivers for PCL6 and Postscript. What if you tried another one?
• If printing to PDF, what happens?
• If you print to that printer from Word/Excel on that T/S, what happens?

If your PDF printing looks correct, how about asking the client to contact their Xerox technician to ask about drivers?