The improved input response setting in video settings does a very good job at getting rid of input delay, but the issue is how jittery it can be. Now Java edition doesn't have this setting, but would appear to have it by default, but when you turn off raw input on Java, it can cause the same jitter that I am experiencing here, so I would highly HIGHLY suggest adding raw input, as this community is very pvp based, and it would greatly benefit everyone, and would cause mouse inaccuracies to go away. 

Edit: I believe it only happens more often with frame drops, but I only have a 60hz monitor, so frame drops can become more of an issue, so for people on lower end devices it could be an issue.