Since you're implementing ICommand instead of simply extending CommandBase, you're required to override the compareTo method. CCubesServerCommands.java#L227. When you do this, but don't actually do the required comparison, it breaks the /help command. I would have submitted a PR, but I likely would have been denied, This is why I am posting here.

This:

	@Override
	public int compareTo(ICommand o)
	{
		return 0;
	}

Should be:

	@Override
	public int compareTo(ICommand o)
	{
		return this.getCommandName().compareTo(o.getCommandName());
	}

However, I would advise simply extending net.minecraft.command.CommandBase and only override the required methods so supers can be called as needed,

Feel free to go ahead and make a PR either fixing the compareto or switching to command base. I know who you are so I trust your abilities to do it right :)