Yes I think the Ukrainians have been reliable in reporting incidents, as far as I know. This incident has probably been confused in the fog of war.
The Ukrainians may have assumed outcomes in certain situations that didn’t turn out to be the case eg all the defenders of Azovstak weren’t killers, maybe because the Ukrainians had important hostages to exchange. The “fuck you” island defenders didn’t all die instantly and some were taken as prisoners , reportedly.
Comms are t going to be 100% reliable. I don’t know what the NATO response could have been to this latest incident. We’ve been down very slippery roads (eg with WMDs) before