This "jerking" is probably happening because you have Repeater enabled FROM the foreground/active window on both PCs, and thus they will both broadcast and fight over the position. If you set a hotkey in your Repeater Profile, particularly the "all windows" ones, that would be part of the problem. If you use the "current window" one, it will work fine.

The issue you're describing where you "click a window and broadcasting turns on" is because broadcasting was already on from that window. It's possible to turn it on from some windows and off from others, and this is most likely what you're running into. For example, if you use your hotkey to turn it on from all windows, and then you use the default toggle to turn it off in the CURRENT window, now it's on in every window but the one you turned it off in. The hotkeys in your Repeater Profile do not sync with the icons. This is why it is recommended to set/use the hotkeys in the Control key map (Activate Mouse Repeat or Activate Repeat) instead of the Repeater Profile.