I've got an E27 of the same design. I'm not buying the freezing issue either, but it may not be a catastrophic failure. There is a ton of info around on how they made those keels.
I'd look at the bottom, grind out the old epoxy and take it from there.
The idea of a severe grounding or lift drop is an interesting one. But, I'm sure sand thing the keel back would show the repair or the damage. There's quite a lot of glass around the keel itself. It you hit anything with one of these designs, it shows up.