Hi,
I detected when I create a new Campaign and I reached the account limit (10.000 campaigns), I receive a new campaign Id, and it seams the campaign is created (the mutate response is returning a new campaign object), but it didn't appear at Adwords website.
I think it should be better to return and error like "ACCOUNT_LIMIT_REACHED", because in some automatic processes where we don't check how many campaign exists for the given account it could produce some misunderstood.
I don't know if this happens too in AdGroups, Keywords, etc. it's something interesting to fix.
Regards,