One of my general courses is about magic in the ancient near east. The miraculous having been made by a wizard, and subsequently the kwamis being giving a form mortals can interact with, is making me think about how that would affect things for other practitioners (I know it's the wrong culture but humor me).
Even if some people in mlb's world have actual magic (like the wizard) then I can still see the same kind of magical practices developing in their world as our world had. Those practices were basically people's attempts to control a world they didn't understand in order to ward off harm like diseases, failed harvests, the evil eye and all that. So even if real magic exists for some people, the vast majority of the common folk would be relying on these practices for their everyday life and probably won't even encounter a real wizard.
One of the things those practitioners did whenever they wrote amulets for their clients (it was a respectable profession!) was invoke magic names that were often said to be names of gods. Considering the kwamis are supposedly gods, I can see their names getting used in amulets and magical spells like that.
They wouldn't stay as simply "Tikki" or "Plagg". For one, the words are going to get corrupted quick as word spreads of those magical names (especially whenever the spells get translated). For another, they would pick up different name and/or epithets by which they can be invoked. (Also, they would probably get merged with other deities as well.)
It's fun to try and imagine the kwamis being worshipped as actual gods, especially in the context of who would be invoked when. Tikki would obviously be invoked the most often considering everyone wants good luck, healing and bountiful harvests. Plagg would probably be regarded as an evil deity or be the ruler of demons, since he would be the one bringing calamities upon people.
It's the other kwamis where there's a lot more variety in how they would be regarded. Or even how people would see them and which would be worshipped (something that would be decided mostly by how useful those domains would be to the everyday of people). Wayzz would be very popular as a protector of all manners. Stompp could be seen as a protector against demons and witchcraft specifically. Barkk ig could be prayed to when trying to find something lost?
Idk, the domains of the kwamis in the show are so trash and don't really lend themselves to actually treating the kwamis as gods rather than mascots. But hey, that's where we get to have fun with worldbuilding! (and it's also a great excuse to infodump about stuff I learned lol).
So how do you think the kwamis would be worshipped if they were treated as a pantheon of gods?
You are dead on the money in terms of the Chinese Miracle Box being rubbish as a proper Pantheon of its own. I think the only way to really make kwamis as gods work is to incorporate all the boxes&kwamis into a broad polytheistic religion.
You could have humans set up some complex celestial mythology for them ala Hinduism, which is probably not accurate but the storytellers get carried away. Another path is a more Chinese style using the kwamis as an aray of nature spirits that are prayed to more generally in the moment and at little shrines. The particulars of each individual kwami/god/spirit and the worship thereof would vary heavily from region to region and even family to family in this case.
How do those sound for starting points?