Met with ECH and SK today, and got everything going. This is what's been done:

• Following my own and ECH's research into the entries which were not converted at the separation stage, I wrote an XSLT file to harvest all of those entries from the unmerged files. SK will check a significant number of these to make sure that we've got all the missing ones. It's possible we may have got others that weren't missing, too; that's not so much of a problem, but I'll probably try to fine-tune the process to keep the numbers of entries down anyway. Then when we're sure we have the correct subset, I'll try to reconstruct the conversion process that the other files went through, and run this file through it. Then the missing entries can be merged back into the existing files as SK works her way through them.
• The schema has been updated. We were working from a 2006 schema with some manual modifications to the RNG file, for two reasons: first, we are using an element (<dicteg>) which has now vanished from P5, and second, at the time when we created the schema, Roma wasn't processing customized ODD files properly (IIRC). Now, though, I've put the whole thing on a more formally-correct footing, and built an ODD file to add <dicteg>, and to modify various other bits of the content model to allow (for instance) <bibl> inside <entry>. At the same time, we benefit from some other changes to P5, such as the availability of @type and @subtype on <gloss>, which enables us to mark editor-supplied (unattested) glosses as <gloss type="u">, making it possible to suppress them or or deprecate them in output if necessary.
• SK is set up on Spartan, working directly on the server copies of the files.
• I have asked for a Subversion repository for the XML. This is going to be essential, since there will be three of us working on the content. Once sysadmin have set this up, we'll have a little training session and I'll make a cheat sheet for SK and ECH.