We found that the string inbuilt attribute within Virtuemart 2 is not using the translatable database tables and the only way how to get it translated is to use language files for all of the inputs. This would lead to creating too many language ini file entries and the work can get very complex when having too many attributes that describe the product. Therefore we had created a translatable string attribute custom field plugin for virtuemart 2.
Enable the plugin within Joomla's Extensions -> Extension Manager
This is the basic configuration of the plugin - the field Title and Description are not translatable and therefoer you do not need to set any speicific values here. The most important fields are at the bottom where you can specify the title of the string attribute.
At the product configuration page, just assing the attribute "virtuemart custom plugin providing translatable string attributes per product" and click save or apply and add the values as needed.
The output would look like this (Language Farsi) at the bottom of the page will get translated.
To customize the theme, you may want to see and edit these files:
\templates\YOUR JOOMLA THEME\html\vmcustom\translatablestring\default.php
\templates\YOUR JOOMLA THEME\html\com_virtuemart\productdetails\default_customfields.php
or at their original locations (pls better copy them to the above locations from here)