Read up
You may want to do some reading on boat construction --Ian Nicholson's books have a lot of basic stuff that is good to know. Ferenc Maté also goes into some detail in "From a Bare Hull". Chappelle is good if you want to go further back and deal with wood. Bending the ends of keelbolts into a J shape has probably been a standard practice since they started casting metal extenal keels in the late 1800's. Using oversize washers to hold the bolt in place in the molten metal wouldn't be stronger and would cost more. As a cost-sensitive boatbuilder (is there any other kind?) What would you do? Your problem definitely needs fixing if you have a gap between the top of the keel and the hull, and the forward bolts are wobbling around, loose.
