[totaltec]

When you use variables in a language entry, they have to be translated by the template that the language variable is used in. So I can put whatever I want between brackets {{whatever}} but in the actual template where this language variable is called, I need to tell the engine what to do with it.

In common_files/mail/html/ask_question.tpl you can see an example of this in action:
{$lng.eml_someone_ask_question|substitute:"STOREFR ONT":$current_location:"productid":$productid:"pro duct_name":$product}

So in your case you are using a language variable that is called in common_files/mail/html/ask_question_subj.tpl

You need to add the
|substitute:"STOREFRONT":$current_location:"produc tid":$productid:"product_name":$product

into the language variable call in that template.