We're not the developers of Joomdle so I've no clue why it can't map the query field. My guess is because the query field is just querying data from elsewhere and is not actually stored to their profile (the _comprofiler table), but that shouldn't be a problem if Joomdle uses getFields API. You'd need to talk to the developers of Joomdle regarding this as I'm guessing they're just pulling data from the database directly to push to Moodle. They can use the below API, which will work for grabbing the data of any field type (including Query fields) instead of accessing raw database data.

www.joomlapolis.com/documentation/279-community-builder/tutorials/18361-obtaining-field-values-through-getfields-api

For their usage they'll want to be sure $output is set to "php" so they get raw PHP values to pass along. This will respond with an array value that they'll need to handle.

The only alternative is to use something like CB Auto Actions to push your query fields value to a text field on login or profile update so it's stored in the database then map the text field in Joomdle.