This is an old problem and I know it’s been brought up before. But it’s still there and it’s still extremely annoying, so I’m bringing it up again: There is currently no way to snap a terrain spline control point to the grid. CTRL-END does not work with spline points. The only way to get a control point on grid is to manually key in the values for all 3 axis for each control point. This is horribly tedious and time consuming.
Actually, UE4’s snap to grid in general behaves oddly compared to other 3d modeling programs. The snap to grid only changes the increments that an object moves rather than actually placing the object on grid.