Ok I put some on some 2 " beaded foam and it really attacked it so if it hits the foam it will damage it BUT here is something that just hit me.

When you sheet foam cores you put a thin layer of glue completely over your core then lay the sheet down. What you are doing there is creating a barrier of glue between your foam and the sheeting thus protecting the foam from liquids touching it. So my suggestion would be to add 2 layers of sanding sealer then you will not have a problem with the laquer based for the wing. I would still test this theory but if you think about it the glue, if any thing soaked completely through the wood, would stop anything from attacking your foam core.

Joe