Buddypress - transalting terms, where to put the files

Hi - I've been researching where to put the .po .mo files after I edit them (I want to change things like 'Forums' to Discussions')

The BuddyPress documentation is all over the place, and old; I have found that in BuddyPress 2.1 and later the language files are in wp-content/languages/plugins - when I place my files in there, nothing. I found a function that I am supposed to add to my bp-custom.php and I'm not having any luck. Basically, I'd love if someone could point me to a straightforward, new-ish tutorial or instructions on how to make these changes. Thank you.