Hello JP -- I signed up for the forum just to file a bug. :-}
I have some JPZ files that I would like to add "descriptions" to and then convert them into PUZ files so that the descriptions show up as Notes (displayed as a Post-It icon that opens the Notepad when clicked) when played on my iPad (Standalone Software's "Crosswords" app).
When I add a description in the XML tags and then use your converter, Across Lite on OS X complains about the resultant PUZ file:
Unable to open crossword: This may not be valid Across crossword or it may be corrupted
Interestingly (or not), the Crosswords iPad app is able to import it without any problems.
As a test, I found a PUZ that contains Notes and that opens fine in Across Lite as well as Crosswords. I then opened it with Crossword Solver, and saved it as a JPZ file. Looking in the JPZ file I could see that the Note was now in the description tag.
Converting that JPZ back to PUZ, I got the same error about the file being corrupt.
The file I tested was an old Merl Reagle puzzle. I've attached it.
(I thought the issue might be odd characters or encoding, so I tested just adding just 'abc' as the description for another JPZ file, and in this case too the converted PUZ failed to open.)
Thanks - I really appreciate that you've built the tool!