I am having a similar issue publishing to JSON server. The form I am publishing is not all that big (max 20 questions), and forms would be coming in fairly infrequently (a few per day perhaps). Oddly, I am publishing several larger forms which are experiencing no issues.
The only way I've been able to solve it is to purge all the data on the form and then retry - which is obviously less than ideal.
I'm a bit stuck on this - and not sure what to take out from above conversation. Has there been any change in the situation since this thread was last active.
It seems that the request to increase writes is only in relation to Google Sheets/Fusion tables, and not for publishing to JSON? Or am I mistaken @Mitch_S and @yanokwa?