I have just used some very dark stain and tiny artist brushes to simulate the nearby grain and cover glue spots and epoxy fills. With just a little practice and care the glue will be completely invisible in the finished piece. Little tiny oval dots of dark stain and some very thin slightly wavy lines are all it takes. You may need to get the artist brushes, but you likely already have some very dark stain that will work. If you don't like the result, sand it off and try again. The key to this is to make it look as close to the nearby grain as possible.
I once filled a 1/2" knot hole with epoxy and then painted grain over it like this. To this day, only I know where the epoxy is.
Charley