I haven't used that recipe, sorry. Just looking at the ingredients, for my own use, I'd have to sub out the cetrimonium chloride. In her online encyclopedia, Marie describes it as "an excellent conditioning agent for hair, with anti-static, anti-frizz, and detangling properties. It also functions as an emulsifier and surfactant, helping boost rinse-off and stabilize emulsions." However, she also notes the very low usage rate due to high possibility for skin irritation. I can almost guarantee that I'd be one of those people, so I've never ventured into trying it.
The DIY B&B recipe uses Honey Quat instead, but that can have a very strong and not-nice smell that has to be covered up with some kind of EO or FO. I use glycerine instead. Since the centrimonium chloride is only 4% of the Vanilla Spice bar recipe, glycerine could be an easy sub for you, too, if you have some around. If not, I'd up the BTMS 50 by that 4%.
I'd also have trouble with the EO blend in the Vanilla Spice bars, which Marie no longer recommends per the update on that page. My skin and blood pressure react violently to even small amounts of those EOs, even when well-diluted. Of course, it's easy enough to leave out the EOs, or use different ones.
Unlike shampoo bars, conditioner bars are quite forgiving when you play around with the recipe. Some folks make them with just BTMS, or only BTMS plus a butter... or BTMS, butter, cetyl, glycerine, and panthenol. The cool thing is that if you don't like the conditioner bar, like a lotion bar, you can remelt it to add more ingredients.
If you do try the recipe, or some version thereof, I'd love to hear back.