Y.W.
These marbles are round with no sharp edges so that's good. How did the 10 marbles you were able to retrieve look? Did they look discolored or did they look about the same as they did when they went in? If they are discolored then whatever the coating was it probably was absorbed by his body. Hopefully they don't contain any lead. I think they should pass through his sysytem like every thing else he eats since the marbles are not shaped in a way that they can get lodged I don't think. Hopefully by the time you read this he will have passed the rest of the marbles with or with the enema.
My daughter put a bead up her nose once and I couldn't get it out. The Dr. ended up extracting it. It was scary for me and her, so I know how you feel.