Another year later, the year is 2017, any changes or updates to this "feedback" ?
Will it ever be added, is it being worked on, or has it simply been abandoned?
Would be great to know.

Hmm, we did some more testing on our server, and did some deep digging on the internet, and it seems there's a limit to 25 keys on the server.
At least that's what we've got. Add 1 more key, and everything "breaks", removing any of the other keys will "fix" it.

I'm having the same issue, it's like we hit an "invisible" limit for the Arma 3 Launcher. Can still load all the correct mods, and start the game, and THEN join on the server. But it's still wierd when it gives Signature mismatch on the list. (Problem happens when adding 1 more key)