You could try to be more creative really. In fact you should. I doubt the devs will do this in Bannerlord. At least change some names around. Since Nords are inspired from vikings it isn't a far stretch of imagination to assume their Polytheism, fascination of ravens, longboats and ship burials. Since Khergits are based on Mongols it isn't a far stretch to assume their worship of the sky and importance of horses. And so on...
I'm sure people will enjoy the mod a lot more if it has some originality.
You're right. But unfortunately, we don't have any canon information right now and we can't simply make things more complex. About the Nords and Khergits, we already did the same thing. Their religions are the reflections of our world's paganism and that means their names are simply changed. Non-reformed pagans are referring as "Pantheon" and reformed pagans has their own Calradia specific names like Steppe Mother and Fylkirate (Not Reformed Norse) which they can be equivalent to Abrahamic religions with all their reformed churches, beliefs etc. just like in vanilla.
So you're using European religions because "Warband mods do so"? Again, I see nothing but being creatively bankrupt from that. And where is Calradia supposed to be, then, if European merchants brought Christianity, Islam, Judaism and Zoroastrianism? Not to mention that they just happen to be located in cultures in which they were in Europe and the Middle East - Judaism and Islam in the steppe, Islam and Zoroastrianism in the desert, Christianity in Swadia, the Rhodoks and the Vaegirs. The only thing you've changed of note is making Catholic into Calradic and renaming the various paganisms.
Yes, yes we are! Finally you understood, congratulations!
Because there is no any canon information for these things. Do you have any idea of ethnology, theology or simply geography? Do you mean we should make Nordic peoples in the desert and making their religions as Pastafarianism for what, creativity? Or I have to ask, do you ever played the Mount & Blade series in singleplayer scenario?
Until the Bannerlord released we're going to stick on real world religions for the majors. There will be a complete changing of map for Bannerlord too! But for now, we will expand and diversify the things while sticking to the lore. You saw our mod what can be look like in our previous developer diaries. Until then, we will wait, and that's what we decided to do, that's what we're doing. Now that's an official announcement for our mod.
By the way, if you don't like, you can always continue to work on your own mod named "Calradia Kings" with your bright and full of creative ideas

.