local addFriend = ERR_FRIEND_ADDED_S:gsub("%%s", "([^ ]+)")
	local removeFriend = ERR_FRIEND_REMOVED_S:gsub("%%s", "([^ ]+)")

Every time I have whisper I see "you added friend" message, even if message was hidden, this is annoying. Can you hide this system message please?

Also you might want to update links to other BadBoy plugins here:
https://www.curseforge.com/wow/addons/bad-boy
They lead to not working domain mods.curse.com

You quoted the code that's in place, the evidence that this is already filtered, so I'm not sure what problem you're having.

Have you changed where system messages are printed?
Try providing a screenshot of the problem.

It's on russian but here is translate:
You added CharacterNick to friend list
CharacterNick comes online
And this is popups every time I get a whisper. When I disabled BadBoy_Levels these popups is gone.

Have you moved where system messages are printed away from chat frame 1?

No, all chat settings is default

Thanks for the report. Try the new update please.