ETC says :

Congo does not directly support XML files, because it is a completely
open standard and there are any number of possibilities for valid XML.

If Catalyst can export a USITT ASCII file containing this data then
Congo may be able to import it depending on the exact subset of USITT
ASCII chosen.

Otherwise, can you send me a copy of the XML file (and any associated
XML dtd or schema files) so I can figure out what data is there and if a
simple conversion utility will be possible?