The keel bolts are doing most of the work - the sealant is there only to keep the join water tight. The weak point is the plywood that should not ever have been used. The best fix is to drop the keel and remove the plywood. replacing it with a heavy glass and epoxy layup.
If the plywood is dry it will last a few years but if (when) it gets wet the keel will move.
Living aboard in Victoria Harbour