Refering to your group question: If you make your game public (for whatever reason), you will not lose any progress you may have done in the maze (cata or map)
Mind you, if you leave the party (when you are alone in your own game) you WILL lose the maze (cata or map)
Now, every time you bump into "sneaky" id suggest you to open the game for a caster to kill it for you. Unless your timezone makes you the only player at that moment, there are guys willing to help you with that quest pretty much all the time (just name the game "help with sneaky" or something of the sort
OR, as its been suggested above, you can also just leave the game and that filthy beast will be gone. BUT killing it gives 7-15 vita points and that's why people do want the quest