I'm playing in this mod pack; "https://www.curseforge.com/minecraft/modpacks/youfoundme" which utilizes Armor Plus as well as the supporting mods "Geckolib" and "TheDragonLib", and in testing, on multiple different worlds, I have never once been able to get a villager to interact with the Soul Box to take on the Profession of "Soul Exchanger".

Steps to reproduce the behavior:

1. Spawn/Find/Cure-your-way to a Villager.
2. Allow Villager to sleep.
3. Place the designated Job Block, "Soul Box".
4. Villager will not interact with Job Block.

In these steps, which I have done all 3 methods of "obtaining" a villager and properly allowing them to sleep so they could traditionally pair to their job block, the villager will never, not a singular time, ever pair to the Soul Box. Unless the process for granting a villager that profession is done differently, I'm leaning to think it isn't even possible.