I'm pretty confused about a few of the photos. What is the first picture that has a rope at the top? It seems obvious that it is the bow, but is it in the anchor locker or in front of the anchor locker? There is daylight just above what looks like a floor of some kind. Exactly what is that compartment and why is there daylight? It doesn't look like the daylight is related to the repair, it must be well above waterline. I also see what looks like 2 bolts, but I don't see a bow eye. Is this whole thing directly under the stem fitting? I'm most curious about where the daylight is coming from. I've seen fiberglass that is almost transparent in corner locations. Perhaps this is the case. It looks like the bottom could be the floor of the anchor locker, but the daylight in that location makes absolutely no sense to me. It looks like it is a hole in the bow above the waterline. There must be some explanation for this.
So the next photo is obviously interior at the bow. Is it under the anchor locker? The hoses make me think this is just underneath the v-berth platform so it must be near the waterline. The bulkhead reinforces the anchor locker, perhaps? The limber hole appears to allow water to drain toward the bilge. This makes sense. It is stained because it is dirty, stagnant water, I think. It doesn't look like a trail of epoxy to me, but I can't touch it to know if it is just a dirty stain or something different. I'd suggest that it is just a dirty stain, which is very common in older boats. I assume that the water might originate above the water line, perhaps at the deck joint. My previous boat had some daylight just under the deck joint, right under the stem fitting. When water splashes over the bow, as it would in steep waves & headwinds, I'm sure some water got inside and needed to drain to the bilge.
I'm only familiar with anchor lockers that are entirely encased at the bottom and sides and virtually water tight except from above. That appears to be the case, obviously, because you have a locker drain. The drain fitting is probably connected to a hose, which is in turn connected to a fitting at the base of the locker. Again, the stain just looks like it's from dirty water. I mean, you are on the Mississippi and the anchor drags up mud, does it not? The trail is simply from drainage that is never cleaned off. I don't see how these stains are connected in any way to the ugly repair, but you haven't really defined the relative positions of any of these features other than we can see that the anchor drain is well above the waterline and the ugly repair is below the waterline.
You did a nice job grinding the repair. I suspect that the previous owner wasn't very careful about nosing his boat into places and receiving some chips in the gelcoat in the process. It looks like there were other repairs made with some gray epoxy that have been sanded smooth in the past. The bow surely has some serious structural thickness with built-up fiberglass. These reinforced areas can usually take some abuse without any structural damage. The gelcoat breaks off quite easily. I suspect that the repairs have been made with epoxy sticks that are commonly available. If your boat sits in the water without leaking, I would be inclined to be not so worried about an ugly gel coat repair below the water surface. Smooth it out and paint the bottom. If you can't explain water that finds it's way to the bilge, when you are just sitting in the water and it's not raining, then I would look into the repair area as a possible source. But if the boat can sit in the water and stay dry, no worries.