If silk touch is disabled in a quest, everytime the player breaks a block his chat gets spammed with a message. Even worse if he has 2-3 more active quests, so everytime he breaks a block gets the message 3 times.

There should be a time limit on it, or a way to completely disable the message.
Or even better, set a check in the plugin that if the string is = null, then dont send it to the player.