First of all, Suffering is subjective. Who's to say, that the shock of a child witnessing how her father betrayed her mother, cheating on her while she was ill, and then witnessed how her mother commits suicide, is lesser than a clone's loneliness, who never knew what it is like to have a mother and a father in the first place? I would say, if Shikinami didn't have an experience to be loved by mother and father, then she never can be crushed by the realization that she will never be loved by them ever again, and she cannot love her father because of his betrayal. Suffering is arbitrary, and it's not a competition anyways.
Second. Why the amount of suffering a character is subjected to makes a better character? If that's the case, Corpse Party and Elfen lied have best characters in history of anime.
To me, It's not the extent of suffering that a character went through that counts when I judge if they are well-written or not. It's how well whatever happened to the character, suffering or not, affects the narrative throughout the entire story. And it's not the case with Shikinami. We know more about Yui and Gendo in NGE than we know about Asuka in Rebuilds. Just throwing "Oh, by the way, clones are programmed, Asuka is a clone, and she has a EVA curse." in the last movie, does not construct a narrative.
She has a EVA curse, because they needed a reason for her to still look 15 after 14 years. Shinji spent 14 years in LCL, why he doesn't have EVA curse? Why he still can eat? Why his hair are not long like Rei's? The answer is, no reason, they needed Asuka be grown in the last moment, to achieve at least some dramatic effect with her.
Clones are programmed, because they needed an excuse for Rei, to care for Shinji in the village, because there was no relationship established between them in 3.0, and in Shin they had no time. That's it, programming serves no other purpose.
The Asuka being a clone thing, was again thrown at as like a bone, to create drama in a completely sterile narrative. The 2.0 was completely rewritten to add Mari. Initially, 2.0 was about the extended story of Asuka with deep dive into her relationships with her mother. But it was cut out, for a girl with big tits who likes to smell people. All of it because Anno really wanted to "destroy" Evangelion. Even though Mari was just a fanservice. I assume Anno was just afraid that movies will not collect enough box office, and Khara would shut down.
Asuka's arc was not resolved, because there was no Asuka's arc in 3.0 and 3+1, because whatever needed to be resolved, was resolved in 2.0.
In 2.0:
Asuka learned how to be kind and depend on other people.
Asuka learned to sacrifice her selfish goals to help others.
Asuka learned how to more honestly express her feelings.
That's it. There is nowhere to grow for her anymore. There is nothing to do. That's why in 3.0 and 3+1 she just sits there and plays video games. There is no real point in her being depressed, sad or lonely. She resolved all her issues. Just like there is no point for anybody to hate Shinji. But they needed to release another 2 movies, that's why they artificially nullified any growth or character developed from first two movies, and just reset the whole thing. Again.
The more I learn about the Rebuilds production, the more it is obvious for me, that the desire to "break" Evangelion, that he didn't want to do it anymore, near the end, that he didn't understand Shinji, and it was more of an obligation, and he needed to free himself from from EVA and make money was at the core of it. Bro, this is NOT a good motivation for doing anything. Just squeezing this shitty story again and again rewriting it 40 times. It really is a shame what it all came down to. At some point he wanted to start the story of Shin from the scratch, because it was not working out. And he just gave up, and said "Fuck it, I don't care anymore." That's why in the end nobody cares if Asuka died, that Shinji says goodbye to Rei, Kaworu, Asuka with blank expression on his face. Anno just doesn't care anymore. In Last challenge of Evangelion documentary Anno said "Animation is a lump of ego." And that's exactly why the ending is so heartless. It shows how Anno just tired and want to stop making evangelion. That's why not only Asuka's but every resolution in Shin, is just a "lump" of Anno's ego, that want's to be done with Evangelion, but he's so disconnected from these characters and from EVA, that no matter how hard he tried, it could only result in realization, that NGE and EOE were better, because without them, the ending is simply empty. The callbacks and easter eggs are in the heart of the ending. In other words, the story of Rebuilds themselves don't hold any weight, and can only rely on the powerful legacy of the original.

. It felt like "oh and btw she's a clone thanks bye". The same move was pulled with Snoke in episode 9 and it felt pointless.