'Murata' was a name brought up in 4.1, as an alternate name of the Graphia family, but there's also a readable about it in 4.2 which reveals that's it's probably the most important thing in Planarcadia's story.
Readable items from earlier patches describe how Graphia ascended an infinite, all-encompassing tower at the end of the world, painting the views from atop the tower, until the antimatter legion invaded Ahatopia and she descended from the tower to save the people. The new readable clarifies that this tower is what came to be known as the Murata, and that it was lost to the World In Canvas after the Cindearth age. Graphia supposedly tasked her descendants with finding it, but no one seems to know what or where it actually is, with the remaining members of the Graphia family treating it as more of a metaphor for Graphia's will to protect her people.
What we know for sure is that there is an infinite existence in the World In Canvas: the remains of Oroboros, an Aeon which could devour infinitely. Its maw could have been mistaken for a tower, too, since in a 2D world it might be hard to tell the difference between an infinite climb and an infinite fall.
There's also the matter of the plot-mandated Stellaron. We know from Evanescia that Aha used the Phantasmoon games to imprison a 'terrifying horror' in the heart of the Canvas, which could admittedly also refer to the Voracity, but a Stellaron does fit the description of an infinite point in space, since it's not a physical object. The Voracity and the Elation do also seem to have tainted each other within the Canvas, since the entity that the Trailblazer meets their shares Oroboros' colour scheme and desire to consume, but also Aha's smile and THEIR obsession with Akivili.
The games themselves predate Graphia- her one minute of Aeonhood was what she used to save Ahatopia- so whatever Aha is using them to contain, it existed before her rather than being something she could have created. That one minute also supposedly cursed her entire bloodline to weathering, but given that the weathering never affected any other supplicant, I'm inclined to believe that it's actual source is Graphia herself. If she originated from the Voracity, then the weathering could be the body or mind trying to consume itself. It also reminds me of the Beauty with Aglaea's erosion- a painter tries to accurately capture reality, with a process of constant refinement just like a Pathstrider of Beauty might. So the weathering curse could maybe be the body's attempt to refine itself, removing its flaws until it no longer exists? That option seems much less likely though, since the Path hasn't been brought up at all.
A Path that has been brought up, though, is the Permanence, which leads to another interpretation of the 'infinite tower at the end of the world, which encompasses all things'- the imaginary tree. Technically, the imaginary tree would be at the beginning of the world, but the beginning and end of Star Rail's universe are very blurred together anyway. Earlier I said that the Voracity could be seen as a tower if you looked at it from another angle- an infinite descent rather than an infinite climb. I believe that the Permanence and the Voracity share the same relationship of the Imaginary Tree and Sea of quanta- they're each other's inverse, but also two components of one greater entity which feeds into itself- infinitely. They even share a Lord Ravager. The wording Dan Heng uses at the end of 4.2- that the Permanence is no longer dormant, specifically- is incredibly suspicious to me. 'Dormant' is the word used to describe Paths that no longer have an Aeon. He says he felt the change after Amphoreus, but also implies that it became even more noticeable in Planarcadia, and he attributes it to the presence of the Abundance, but the Voracity seems more likely.
Going back back to the part about the two Paths sharing a Lord Ravager- I'm starting to wonder if the Permanence and the Voracity are even separate at all. They share a prime mover related to selfishness; isn't devouring something the same as refusing to let go of it?. Both Aeons are leviathan-like, and associated with the cycle of life. What if they're a singular Path, misperceived as two separate ones because they appear differently depending on what angle you look at them from? And that's why the Permanence no longer feels dormant on Planarcadia: an Aeon of Permanence is present, in the form of Oroboros' remains. We also know that Graphia is still alive, and while she probably wasn't human in the first place, if the Voracity was also the Permanence then it would be able to extend her lifespan.
And since the imaginary tree is involved, that links to two other characters:
Aha, who's said to have ascended to Aeonhood by climbing the imaginary tree and beholding the universe in all its entertaining futility. Graphia's story is the exact opposite of THEIRs: she beheld the world and found meaning instead, so she descended the tree.
Murata Himeko, the original one from HI3. I don't think she's alive, but she did fall into some kind of infinite space after dying, probably the sea of quanta. We also know that she's part of the reason Welt came to Star Rail's universe. The Murata within the Canvas, or Graphia herself, could originate from this Himeko, and the weathering curse is strikingly similar to the Honkai corruption that killed her.
Given Star Rail's writing habits, I'm leaning towards all of the above. The Murata probably simultaneously relates to Oroboros, Aha, a Stellaron, the imaginary tree/sea of quanta, and maybe Murata Himeko.