I recently played a modpack called SevTech that implemented the recipes for a Tier 6 altar by combining all will crystals with an awakened catalyst, but I noticed that it is not available in "vanilla" Blood Magic.

Is it currently possible to make a T6 altar by using the old layout and topping the pillars with the purple demon clusters?
Seeing as they're a creative mode only item right now, one would just have to add a recipe to reach T6 then, or not?
How could I do that for my own playthroughs?

Version:
Blood Magic: 1.12.2-2.4.1-103.jar

This should answer all your questions: