[abescalamis]

Does anyone knows how if there is a way or program to add the language suffix to the subtitles, after days investigating I found out that Fileboot can do it but it looks like you will need to use a script but don't know how or where to run it and seems to be beyond my knowledge. 

All I want to do is add the .eng. or .spa. to the subtitles.

[Klojum]

There are plenty of (batch) file renaming tools available in every operating system.
Find one that works for you.