Hi, warning: I know nothing, so please be patient and answer as if I am 5!

My tub drain and overflow drain are separate / not connected (only in that they use the same drain pipe).

When I remove the overflow drain faceplate there is a space of about 1/3" between the actual overflow drain and the fiberglass tub wall. It seems to me water would be flowing down the back of the wall (not quite making to the drain) which wouldn't be good.(however I have no leaking below tub etc).

I don't think tightening the faceplate more could get the drain and wall to meet (too much space in between).

Right now there is a big thick grey rubbery (seems like foam??) round gasket in between the wall and the overflow drain.

Is the water supposed to flow through this mystery gasket to go down into the drain? Wouldn't this gasket get soaked with water?

1) Is this the proper solution to fill this space between overflow drain and wall of tub?

2) Also the overflow hole in the tub wall and the overflow drain don't line up exactly, they are about 1/3" off. So this big thick gasket is also trying to make up for the offset. Is this an ok solution?

I don't have leaking at all, and don't want to really cut a new overflow hole into tub to align them such a small amount.

Is this gasket thing the way these 2 issues can be solved? Or should I really do something better?

Thank you.