If it helps, I've done an XML dump.
For the strange characters, I have the following inside a record:
<f n="Transaction_Comment"><![CDATA[愀氀 爀甀]]></f>
When I go to that transaction inside iCash, and try to replace that comment with something else, it looks for a moment as though it has worked, but then reverts to those strange characters.
And I've seen that all my transactions with the strange mashed-up comments are all in a block of transactions immediately before this one with the strange characters.
I can manually fix this xml file, but can I start up a new iCash File with the fixed xml file?