TableListField headings translation doesn't work.
The problem is in TableListField.php file, line 351, in Headings() function :
"Title" => ($this->sourceClass) ? singleton($this->sourceClass)->fieldLabel($fieldTitle) : $fieldTitle,
shoud be :
"Title" => ($this->sourceClass) ? singleton($this->sourceClass)->fieldLabel($fieldName) : $fieldTitle,
I've opened a ticket (http://open.silverstripe.org/ticket/5742) with a patch.
Hope this help :)