Denial

Does VICE or any other Vic emulator translate the mouse position over the emulated screen to light pen X,Y?

Indeed VICE supports light pen emulation with the mouse. You find it in the "Settings ..." menu.

Here you find a example application, MINISKETCH.

Note the physical resolution of the lightpen (registers) has a 4-pixel granularity in X and a 2-pixel granularity in Y direction. It also needs some quite involved code to check whether the lightpen is it at the screen at all (I use a simulated lightpen event at a Y position outside the visible screen for this).

Finally, the lightpen needs a bright background to work properly - using a black background is no good idea.