There is a wide gap between what the Church believed and what a particular ruler understood of the religion upon conversion. Because a king's conversion often came with mass baptisms (including upon Clovis') one can understand why they wouldn't have stressed the king understanding every minute detail (not to assume that I fully understand the motives if early medieval French bishops).

So, to quote Gregory of Tours on the conversion of Clovis, "The priest, little by little and secretly, led him to believe in the true God . . . and to forsake idols, which could not help him nor anybody else.". I think this clearly indicates that Gregory at least adheres to monotheism, and not monolatry, and it's furthermore suggested that the priest in question does so too. To wit, idols being useless indicates that they are not linked to any power, implying that there is no supernatural power other than the God of Abraham.

The change from monolatry to monotheism happened long before Christianity came to be. In the octateuch we get stories like Pharaoh's magicians turning rods into snakes, or the witch of Endor calling Samuel's spirit from the dead, both implying powers aside from the God of Abraham. But I think you'd be hard pressed to find anything explicitly set after the Babylonian captivity (sixth century BCE, well before Christianity develops) which leaves any room open for a pantheon. I did a search for "idols" in the Bible, and came across choice NT quotes like 1 Th 1:9 "and how ye did turn unto God from the idols, to serve a living and true God," again indicating monotheism, and Rev 9:20 "that they may not bow before the demons, and idols, those of gold, and those of silver, and those of brass, and those of stone, and those of wood, that are neither able to see, nor to hear, nor to walk," which indicates explicitly that idols are material objects and not representatives of other gods (and also brings upon the issue of other gods being demons, which is a whole thing I don't want to get into and is a completely separate issue).

I wish I had more to give you, but you're question is simply a bit off base. It's not the case that the Church ever had a monolatrous position, as can be from your chosen source (Gregory), or from the NT (I hardly scratched the surface, only finding the fastest results I could) or from really any early Church father you want. I'm frankly too lazy right now to find quotes (sorry) but you might want to read Justin Martyr's letters to the Roman government (he argues against the accusation that the Christians were atheists by asserting that they believe in one God) or Augustine's Confessions (recounts in detail Augustine's journey to Christianity) or the Nicean Creed (predates Clovis' conversion by centuries), etc etc etc.

Okay, what you want to ask is what I clumsily brushed aside at the start of this reply, to wit what was the process by which individuals who viewed Christianity through a monolatrous lens came to be accepted within the Church, how did they influence Church development, and how long did their perspective last. A common accusation against the Catholic Church is that praying through saints developed to appease monolatrous converts who were unready or unwilling to accept the Church's monotheism. In other words the Church began at a strictly monotheistic position and evolved towards monolatry, not the other way around. But that's a whole can of worms, and I don't really want to rehash the Protestant Reformation right now (I'm already in my pajamas).

This reply frankly isn't the high quality this sub deserves, but the answer to your question is simply "the Church was never monolatrous".

Edit: oh, also look at these answers [here] (https://www.reddit.com/r/AcademicBiblical/comments/9gcdcs/when_did_christianity_move_away_from_the_concept?sort=confidence). Unless you posted that x-link.