I couldn't find anything indicating that Piercing was supposed to be exclusive with Efficiency. Tested on the 212 version of Quark for 1.14 with nothing else but ARL installed, and the two enchantments refuse to co-exist. Ended up deleting my 'rang and redoing the enchants without Piercing, because Pickarang without Efficiency is fairly lackluster, even with Piercing. If this is intended, I apologize for bothering.

This seems like as good a place as any to say that the Pickarang is the best thing to happen to my Minecraft setup in awhile. I was still using the little monster in late-game Enigmatica Expert instead of my fully decked-out DE staff, because it just did some things better. Kudos to the Quark team for the best multitool in modded Minecraft.