Bug in Advanced Tools / Translation (I18N)?

Problem / possible bug

With the localisation turned on, as soon as a translation for a particular field is added, the corresponding field shows up empty.

The particular fields are constructed in a JDBC-query.

Figure 1a: translation correct / no values

Figure 1b: corresponding translation

When I turn of the localisation the values of the fields show

Figure 2: no localisation

When I leave the translation for the particular field blank the values in the fields shows. Of course the fieldname isn't translated.

Figure 3a: no translation for term in I18N

Figure 3b: corresponding translation

Diagnosis?

I use a JDBC Datalist Database Binder to construct the problematic fields i.e. FULLNAME_ASSIGNOR and FULLNAME_ASSIGNEE. Can that be the problem?

Figure 4: JDBC settings

JDBC-query:

SELECT id, c_Task_Name as 'Task', c_Task_Description as 'Description', c_Task_Assignor as 'Assignor', c_Task_Assignee as 'Assignee', c_Task_Deadline as 'Deadline',
(SELECT CONCAT(firstName, " ", lastName) FROM dir_user WHERE dir_user.username = app_fd_MB_Task.c_Task_Assignor) as Fullname_Assignor,
(SELECT CONCAT(firstName, " ", lastName) FROM dir_user WHERE dir_user.username = app_fd_MB_Task.c_Task_Assignee) as Fullname_Assignee,
CONCAT("<img src='http://localhost:8080/jw/web/client/app/001/1/form/download/frmTask/", id, "/", c_Task_Image, ".thumb.jpg.' height='100' width='200' align='middle' />") as 'Image'
FROM app_fd_MB_Task