Hello.
I want to inform you that I was able to destroy CompactMachines walls (being inside of it), by item Vajra from Gravitation Suite mod. It is possible to break this walls using Vajra's built-in silk touch mode (it is right click to a block).

Report this to the Gravitation Suite mod. They are allowing unbreakable blocks (with a hardness of -1) to break. Not an issue of CMs.