As per Organized Editing Guidelines on https://osmfoundation.org/wiki/Organised_Editing_Guidelines, there’s a set recommendations, being one of them expect of organizers document activity before starting (and with plenty time for local community give feedback, with suggestion of minimum 2 weeks) under https://wiki.openstreetmap.org/wiki/Organised_Editing/Activities.
However, organizers of an event might decide to NOT document their activity on the OSM Wiki. And, by the time the complains starting coming because of data issues (and which, by the Organized Editing Guidelines, this make the recommendations there not as optional), there’s no archivable, public, central place which the mappers not involved in the event can submit their complains. Yes, I’m aware these complaints might not be resolved. It even answered beyond the “thank you”, however it is still a good reference for any future mapathons of the same organizers and the local mappers which likely will have to clean up if the same problems happen again, just in another place.
Then, while feel free to make other general comments around this topic, my main question is if anyone can start documentation of an activity in the OSM wiki without waiting for the event organizers.