Get kills that are not mine and vice/versa

1) sounds like something that actually is a consequence of intended mechanics - if you kill someone in motion of throwing a grenade, his grenade becomes 'yours', giving you the kill (or, in that case, suicide). 2 might technically be possible the same way, although you should get both M67 and RGO kill. I can't really explain 3), normally it only happens when you get killed by explosives that you shot with a gun (like Claymores or Slams). I recall seeing 4) at some point, but I don't remember what triggered it. 5) happens if your grenade flies too close to any kind of edge - the fire cloud is displayed in the place where you would expect it, but in reality the grenade bounces off and lands by your feet. 6) is something I haven't seen yet. With current M34 mechanics, I would expect that it landed behind some sort of a small ledge, resulting in no damage (and someone else did it with, for example, M67 or RGO. 7) is almost certainly a latency-related issue. Kind of like dusting on vehicles. 

All in all, it sounds like a mix of issues that can't really be fixed on player's end and some possible coincidences, unfortunately. While reporting this on CTE subreddit is an option, I don't really see any way for fix to come soon, especially if there are no surefire ways to reproduce the issues.