I feel like Yun-Jin's lore has gotten less credible as it's been expanded
First off, don't get me wrong. I completely understand that her driving motivation is to stay employed and that she has reasons not to turn in the Trickster even if she does suspect him; it would stain her name and ruin her career. And I like her that way - she's not a bad person, but she's not a good one either. We could use some less unambiguous altruists in the survivor roster. And three entries in this rift haven't been released yet, so who knows, maybe it'll all come together.
But. Previously, the basis of Yun-Jin's suspicion was thus: there was a string of murders following the band around, completely unconnected to Ji-Woon. Then she came in one morning, where he was already there and looked exhausted, and in the weird screamy intro to one of his new music tracks, she heard a scream that she identified from a missing persons video. This was seemingly the turning point in their relationship, on both a personal and professional level - but what I like about this hook is that this is something that would be easy to fool yourself into thinking you misheard, that you were imagining something that wasn't there. It's a very tenuous connection and while you can condemn Yun-Jin for not looking further, it's also a very human thing that she didn't want to.
Now, in addition to this, she's got:
-A murder several years ago where she recognized his very exclusive headphones on the suspect footage (so something that definitively happened before the sound clip event)
-Another more recent murder where he was one of the last people seen with the victim and was next seen with fresh scratch marks
-Him constantly dodging and bribing his security detail
-A private soundtrack full of authentic screams, completely unadulterated or passed off as music
-Whet stones and knife cleaning products in his room
-And everything that goes down in the next three entries.
It's gone from less of a disturbing, sleepless-nights sort of possibility that her coworker could be a murderer to the point where Yun-Jin would have to be stupid to think he might not be. Like, she has everything but his signed confession at this rate, and getting the Trickster to put his name on something would be a piece of cake. I'd like to think that at some point, she'd cut her losses and turn him in, because she's too smart to think this can last forever (the Trickster is constantly slipping up and giving clues, he's not good at flying under the radar) and she can still spin herself as the hero if she handles this on her terms rather than the police inevitably busting this open. Or she can drop him immediately and distance herself as much as possible. Something.
I understand that her tension with and distrust of the Trickster is the driving force of her story, and the rift would want to work with that juicy material, but I don't think continually expanding on that one point is improving her overall lore. Sometimes less is more.