The problem here is not that unanticipated outcomes arose from our intended fix.
The problem that the exact edit we planned isn't happening in the first place, because the search-replace tools aren't yet specific and reliable enough.
When the sections are subsequently rejoined, entire gene segments may be misaligned or missing. The medical consequences are unpredictable and, in the worst case, contribute to the development of leukemia.
Specifically, there are three copies of the gene, the active one and two inactive ones. Trying to only edit one, they ended up hitting ay least one of the others as well. That then caused misalignment and other issues for the rest of the neighborhood.