You don't need to convert a catalog, you can select to create it as a Mobi format . Just change EPUB to Mobi (it is a pulldown)
You have a Read column.
On the Catalog configuration page that shows in the Beginning, There is a second Tab 'Ebook Options' there is a section to specify which column to use tor Read Status.
Next to that is the place that must be set to the
value that
indicates read