Hello.
Quantized notes and cc data are consistently positioned slightly to the left (earlier) of the grid position.
Oddly, the early part of these notes can be selected with the mouse when left-clicked on, but cannot be selected with right-click range. The right-click range works only when it extends to the "correct" part (to the right of the grid line).
Reaper 5.29 x64, Windows 7 x64