Are you trying to enable the calendar(s) on the primary Gmail account?
If not, I don't think this method will work. I have been unable to set up any calendars other than those associated with my primary Gmail account.
Btw, following a reboot, I normally see that the file which I edit reverts back to the 'enabled' and 'syncable' entries missing.
Only on my secondary Gmail accounts do I ever see the enabled="false" flag.