The big issue with the depiction of Eldar in art is that it's always rather generic Space Elves. Lore-wise (usually) Eldar would just kickoff every sense of uncanny valley you have into overdrive. It's full on wrong proportions and wrong movement like a Skinwalker.
A big part of that though is the way they
move. And that can't be depicted in static artwork. Imagine even a normal person with normal proportions, but he never blinks, never twitches. When he moves it's unnaturally precise and goes from motionless to Bruce Lee strike, even when performing ordinary motions like picking up a mug to drink. And he stares at you the same way a lizard stares at people. You've removed all the non-verbal human queues of communication. They're there but they're alien and they're so small that the man seems like a robot. When he speaks, he gets your language almost perfectly but there's just something slightly wrong like it's not his own. Even without the alien proportions he is deeply disconcerting, coming across as something unnatural and possibly sociopathic. Eldar are a species that can jump six foot in the air from standing (c.v. Howling Banshees, Harlequinns, etc.). They're like coiled springs. Combined with their weird poise and agility, imagine what they're like to be around. A position that would be uncomfortable for a human to maintain would be nothing to an eldar. According to the lore, Eldar are physiologically closer to reptiles than to mammals.
I'm therefore a bit forgiving of eldar in art. But the artist still needs to understand they're not human. IMO, good and bad depictions of eldar in art:

Now paying no attention to any other merits or flaws they each have or preferences for style or detail; the first one looks much more unnatural than the second. In a good way. The druchii woman has human face proportions, human body proportions, limb thickness, etc. And height is human as well. The first one, you don't even need the presence of a human next to him to feel that he looks about 8' tall and weird as Hell. Imagine that thing stooping through a door and walking into a room with you. You would be disturbed.
True but Cassia can see emotions, it's not impossible for her to come to term with the fact Rogue Trader is not doing anything inappropriate with Yrliet (beyond consorting with xenos, that is but if that's an issue, look at Heinrix)
Cassia has the emotional development of a child. Girls like that get jealous of anything that takes your attention away from them. They'll message you all day long while you're at work simply because they want to make sure you're thinking about them. It's way worse if it's a woman you're spending time with. First you spend half your time convincing Cassia that you are attracted to her even though she's a freakish mutant whose weirdly tall, socially strange and has an extra eye. Then you have to spend half your time convincing her that you're not attracted to Yrliet because Yrliet is weirdly tall, socially strange and has eyes at 45 degree angle. Yeah, you're wildly overestimating the rationality and independence of women like that.
You're also engaging way too seriously with what was intended to be humour!