OK. So, it's not an auto-generated file, right?
In that case, I would prefer to find a good source of speedcams locations, instead of trying to modify the ones in the routes I usually drive. In roads I usually drive I remember most of them by memory anyway.
I think it's more important to get the correct notifications in roads I pass for the first time and of course I can't have modified these cameras myself beforehand, so a good source with reliable data is the most important thing.