Tbh, I haven't much extensive experience with BI's religious influences. The only campaign I completed was a Roxolani one (VH / VH), soon after BI was released, and that's about it. S'pose I would've seen the in's and out's if I'd played a WRE, ERE, Sassanid etc campaign and experienced such results first hand, but otherwise I'm reliant upon the judgements made by others in such areas.

At the end of the day, the AI is can only work to its limitations. Traits and triggers could be setup to help the AI as much as possible, but it depends entirely on the AI's actions on the campaign map, and more often than not these are predictable.