420's the stuff. Yeah, the compression side is worse than the back side. My guess is that a long sliver like that will have sort of a long lever arm to want to keep pulling away again. On the other hand,it's a bigger glue surface, so.... Have had some success fixing cheaper recreational bows for newbies and kids by actually removing that sliver (cutting it off)and pouring 420 into the gap. Not a cosmetic solution, however.
The most dramatic one I had was a 57# Bear Cub from the mid-fifties. It was missing a chunk of glass on the back side....about 4" long x 1/4" wide and nearly the full depth of the glass lam. As a test I poured 420 into the gap-it soaked in of course-and then I put a piece of shrink-tubing over the hole, so that the ends of the glass fibers wouldn't be able to raise. The crazy idea worked! Didn't look too bad from a distance: black shrink tubing on black glass. I shot a couple hundred arrows from it and then sold it for $25. It was a very good shooter. The guy that bought it sent a picture about two years later of himself and a deer he killed with it! You never know until you try.