White glue is nasty stuff, and it is almost impossible to undo damage caused by it once it is done. The bond will harden stronger that the wood it is joining; and the chemical composition is inconsistent (the producing companies use different mixes depending on what is available and cheap), so there's no set formula for diluting or removing the glue once it has dried. I'd stay away from white glue if I valued the instrument I was repairing.