[BUG?] Custom field translation not in email

[zebrafilm]

I am using boolean custom fields for a yes/no selection and use it on a bi-lingual site. My TAG gets properly converted/displayed on the website and in the invoice/ PDF in the orders overview but not in the email or PDF invoice that is send to the clients and admin.
So it seems everything that goes 'off site' misses the proper translations.

Bastiaan

J2.5.4 / VM207