I have a pack i am working on and i really like the tool, however one of the tools in my endgame (that are worse then yours) is able to break bedrock where yours cannot.

Just a config option defaulted too false is good, just would like to enable it to be of the same use as the tool.

No feature work is being done for 1.12

Multi-Tool has no special code to prevent breaking of bedrock, it does everything based on hardness and the invulnerable flag. I would not add something special for one block without making it configurable for all blocks. In 1.15 there are easier ways of doing something like this that I may explore, but for now now.

In general though something being invulnerable means its only supposed to be broken by its own mod, normally for game-play or other reasons. Making something that breaks that normally just results in an escalation of them trying to find a way to prevent it (think thaumcraft warded blocks).