From the article on SA, not sure that the actual why these two keels have failed has been said yet. Look at how long it took the CG to figure out/say what happened with the CF38 in Texas. Hopefully it will be known for both at some point in time. Be it J-boats and not building as strong as it should have been, or previous owners grounded, and damage was not fixed, or unknown or unseen until a failure occurred. Fortunately, neither time from what I recall of the other indecent had injuries or deaths. Just shook up folks! Which not that one likes to see shook up folks, better that than injuries or deaths.
While these issues would make me think twice about sailing one, not sure it would be for long. Been many issues with keel failures with rigs and deep bulb keels, like the J80, Giuletta's design, or should I say the design on Giuletta etc. There may be some issues that we as humans have not figured out, planned for with the speeds etc we are driving these boats. Harmonics was something brought up, that may not be figured into the design.
Please note, my thoughts only, not trying to push blame on anyone. I believe generally speaking, J-boats are good products, and worth looking at for a next boat for me any how. There are too many issues with some keels falling off right now. IIRC, the british rag "Yachting World" last year early in the year did a series of articles on some of the keel failures around the world, some why, some questions still un answered etc.
She drives me boat,
I drives me dinghy!