I personally think KJ is in a rough spot where she's certainly overpowered but one nerf and she may fall to totally useless. on a similar but another hand i think cypher is totally balanced, just out shadowed by current KJ. Sage works as a niche pick and Chamber can remain garbage forever and i'd be happy.
If I were to make any changes, I would just nerf KJ's ult, and i would either shorten the radius a little bit (for example, making the common ascent B main ult unable to cover all of backsite) OR cut the detain time a good amount (maybe make it as long as gekko detain? it'd be a two second nerf). Not both, at least for now. Turret and alarmbot are fine. Idk what i'd change about swarm grenade, i think it's fine too though