I'd be unable to sleep worrying about whether one of my - should really be a +, or whether I stumbled on one step of "index gymnastics". Or I'd be wondering if

I'd be unable to sleep worrying about whether one of my - should really be a +, or whether I stumbled on one step of "index gymnastics". Or I'd be wondering if someone would ever spot the deliberate <https://en.wikipedia.org/wiki/Beatosu_and_Goblu https://en.wikipedia.org/wiki/Beatosu_and_Goblu> trick of changing a single \mathrm{B} into a \mathfrak{B}. Or both. However, the authors are in close communication with many of the other authors in their extensive bibliography whose work this follows (and in turn who likely be provoked into further work). The progress (seen in the paper's review-like parts and the bibliography) has been towards proving that less and less "gentle" vacuum spacetimes aren't irrevocably upset by gravitational waves passing through them. The bibliography cites a number of pre-pandemic preprints that were in "to appear in <journal>" state. In that sort of academic bubble, which is far from unusual, errors are liable to be found fairly quickly. Also I would guess that the authors revisited their self-cited previous work, which sometimes produces forehead-smacking.