@dweb2012
If you are comfortable with GitHub, then you can download and use the 2.1 branch of this plugin, which supports the standard WordPress translation methods (of both the user interface and printed data). This branch is not yet feature complete, but in testing seems to be reliable, and it is fully translatable.
Alternatively, in the current release, all strings that are used to create the print job can be found in the file order-handler.php. You can edit this file to translate the current, released plugin version.
Unfortunately, both approaches require some development, until we officially release the 2.1 update, which is likely to be next year.
