I believe I've managed to find something here. I'd like to expand onto this ticket I made here T168507: Movement Data cfggameplay . So it seems that any changes you make to the "Movement Data" in cfggameplay.json does work, BUT when you load into a server with your custom character, it looks janky and looks like if any of the changes weren't saved. But if you kill your character and randomise it to a different character, it will be fine. As long as if you don't end up randomising onto a character that is the same as your custom character or it will look janky again. Example Videos Below.

In this video here (above), I am using my custom character and I have made edits to "timeToSprint": and "rotationSpeedSprint": to 0.1 only. If you can't see, the character is a little janky and jittery when getting to the sprint and rotating on sprint.

In This video here, I have selected a random character. If you can't see, there is absolutely no jittering or jankiness going on which means the movement data values are working fine. I don't know why this is happening but I have tested this with someone else and we have both gotten the same results. Just something I noticed.