Since I've become sysop, XML files with real content are backed up to Incubator's File: namespace. Before that, I think if XML files exist they're on the individual computers of the deleting sysop. If there was no legitimate content, there is no XML file.
From: Phake Nick <c933103@gmail.com>
Sent: Tuesday, August 28, 2018 3:46:24 AM
To: Steven White
Cc: Wikimedia Foundation Language Committee
Subject: Re: Eligibility of Pinyin Wikipedia
As part of the discussion, someone asked where can one obtain archived xml file for other deleted incubators.