Well, there is a way. One of the "secret" features of Cardbox is that the menus can be translated. If the Cardbox folder contains a textfile such as "cbxm####.txt" where "####" stands for the country code, Cardbox will substitute its English menus/messages for the translated menus/messages from the file.
For instance, the Dutch file (cbxm0013.txt) contains the following:
Cardbox will not use this file unless you tell it to do so.
If you would use a similar file and call it "cbxm0809.txt" (0809 = English), Cardbox will substitute its English messages without you having to tell it to do so, because English is the default language.
If that file looks like this:
Creative solution. However: you cannot force Cardbox on a cd to start with another language default then UK first time...
It's a registry setting (and not -a pity!-) a workspace setting.
Best solution could be writing a script that fist changes setting HKEY_CURRENT_USER\Software\Cardbox\Cardbox 3.0\User Interface\Language, then launch Cardbox.