I would suggest restarting your server after you change the config to completely reboot your new config option.
Before minecraft or bukkit is running, I edit the config.yml and change the RevertEarth setting to false.
I then start the bukkit server, then minecraft, and get on the server.
I raise a couple pillars of earth, then exit the server.
If I simply get off the server and get back on, the pillars are still there.
If I completely shut down the server, then start it back up, any earth I manipulated with my bending is gone, and the terrain is back to normal.
I don't know if this has anything to do with it, but these lines were in my log file:
[18:57:16] [Server thread/INFO]: [ProjectKorra] Enabling ProjectKorra v1.3.0
[18:57:17] [Server thread/INFO]: [ProjectKorra] EarthSmash: Loading Config
[18:57:17] [Server thread/INFO]: [ProjectKorra] Suffocate: Loading Config
[18:57:17] [Server thread/INFO]: [ProjectKorra] [ProjectKorra] Establishing SQLite Connection.[SQLite] Connection established!
[18:57:17] [Server thread/ERROR]: [ProjectKorra] Plugin ProjectKorra v1.3.0 has failed to register events for class com.projectkorra.ProjectKorra.TagAPIListener because org/kitt/tag/AsyncPlayerReceiveNameTagEvent does not exist.
[18:57:17] [Server thread/INFO]: Server permissions file permissions.yml is empty, ignoring it
[18:57:17] [Server thread/INFO]: Done (4.299s)! For help, type "help" or "?"