Hi just fixed the issue, here's my solution:
Edited the DOM:
1. dataobject_manager\templates\ImageDataObjectManager.ss line 6
2. dataobject_manager\templates\RelationDataObjectManager.ss line 6
3. dataobject_manager\templates\DataObjectManager.ss line 6
From:
<span class="uploadlink"><img src="dataobject_manager/images/add.png" alt="" /><% sprintf(_t('DataObjectManager.ADDITEM','Add %s',PR_MEDIUM,'Add [name]'),$AddTitle) %></span>
To:
<span class="uploadlink"><img src="dataobject_manager/images/add.png" alt="" /><% _t('DataObjectManager.ADD','Add') %> $AddTitle</span>