I'm not sure what you mean by editing the lato font. But overriding would require custom coding to do so. I can let you know where the font is called if you need help finding that.
I have 2 requests:
1st: I want to add lato (exist in Google to my vertex fonts so, I can pick it)
2nd: is to edit Read more of the news module (MOD_ARTICLES_NEWS_READMORE="Read more...")
because I can not find it via language tab search in joomla! However, I can find the file you've mentioned in the FTP!