As you wish ,
The answer is simple , in the windows version of AATOFL and Milky ways Zip file is a folder called "Story mod tools"
in this folder you will find a tutorial on how to use it in doc format as well as the tool itself.
It is not really trivial to use but with this you are able to change about 99 % of all text in this game. But.. as i said... you maybe overwhelmed by events and text.
ANd btw , you may want to look into the story mod manager , some peopel already started wit ha spellcheck file but never finished it. you may want to download one , start the game with mod support enabled and then re-export the file so you can actually work on the latest version.