So, I'll embrace the Chrono Trigger references in this regard, because I've been doing a Let's Play of it recently, and as such, have been ruminating both its translation/localization and JP scripts.

In Chrono Trigger in the infamous kingdom of Zeal(Jiru) there is a town of dreamers, Enhasa. In that place, the citizens of Zeal embrace an almost constant state of sleep in order to have dreams. Here you meet a creature named Doreen, who is strikingly the same as two creatures you met much earlier, Masa(Gran) and Mune(Leon). In English you go on to find out that these creatures are related, siblings even, but only two of them are part of a certain sword.

Well, if you dig into the differences between the English and JP script, you will find a line that was omitted/altered that fills in a huge gap that I wasn't even aware of until I read the original line. In JP, one of the dreamers of Enhasa states something along the lines of, "The creatures of our dreams sometimes materialize." It's phrased a bit more vague than that, but the implication is that the dream trio were brought into existence via the Enlightened Ones' dreams. This same NPC says that the power of Lavos-sama is what makes it possible.

Now, obviously we can't really draw 100% line for line, blow for blow comparison here, but Shadowbringers directly references Shakespeare's, "The Tempest." and also the movie, Forbidden Planet(which is also heavily inspired by The Tempest). In Forbidden Planet, the Krell destroy their own civilization by inadvertently making the monsters from their dreams a reality.

Were there to be a Lavos-like entity, whether they want to call it that or refer to it as the FF7 alien-parasite, or something else entirely, it would fit right in with this setting given this context. Also, given the OP is referencing the Ronkan murals, do note that the first monster you fight in the Qitana Ravel is a, "Ronkan Dreamer."

Really gets the imagination flowing, huh?