Read entire post first.
Actually I cant quite tell if this is the solder side or component side or in your case.
a) Where the leads poke thru or the other side
b) Also not sure if the capacitor is surface mounted.
c) We can't tell if the hole is plated-thru to the other side and connects to something of value.
So, if we assume that the cap leads poke through this side and nothing of value connects on the other side. then:
Clean the holes in the foil if not surface mount which I think it isn't.
The epoxy adhesive glues the trace to the board. Let dry.
The idea of putting say a small ring of contact cement on the diameter perimeter of the capacitor makes some sense. So does hot glue and so does electronic grade silicone. Aquarium seal should work. It can't have acetic acid in it. The idea is to prevent water infiltration, not glue the capacitor to the board.
The board looks like it has a conformal coating on it. the only real way to remove this is usually scrape. Solder won't stick to this stuff. Also see:
https://www.newark.com/techspray/2510-p/conformal-coating-remover-1pint/dp/69K7673
After soldering the flux has to be removed. The soldered and cleaned connection could be covered with clear nail polish or a real conformal coating. See:
https://www.newark.com/techspray/2103-12s/acrylic-conformal-coating-aerosol/dp/68K7372
So, we can't 100% answer this without seeing both sides of the board and the removed capacitor.
In rare instances the board could have more than two layers.