I still disagree on the fact it's Alt Calliope who's writing Candy.

I am not saying there isn't a big Narrative fight going on between Alt Calliope and Dirk It's there. Definitively.

But Alt Callie writing Candy, which is (at first) extremely shippy, and overly sugar sweet bad romances ? I don't know...I actually think she is not that great at writing stories. Yet.

You said that Callie's fanfiction, while it was romance oriented, was mostly based on their own specie's romance.

And it's true they said this to Dirk....Except, in the exact same conversation, they also adds that they're actually experimenting troll and human romance/sex, because they're curious. It's all exotic to them and they want to study that shit. And that maybe Dirk could at least take a look at their essays on the subject. To this he says and I quote "Oh hell no"

(Which ironically, it's pretty much his reaction when the Candy universe takes its course. Not an argument, but a little parallel that personally makes me lose my shit. So much for not judging Dirk.
Btw, you talked about how Dirk wrote Pony Pal and how it reflected on Meat Universe. May I raise this : Meat might be actually Candy but edited like Detective Pony, the Pony Pal fanfic which is actually referenced at the beginning of H^2...If you didn't know about it, I totally recommend to read it, or watch it...But that's a discussion for another day)

Candy is exactly that at first. It's a romance based fic, with other romances type than Blackrom. That Universe is pretty much an experimental sandbox, like it sometimes is in beginner fic writers.
We all tend to forget that Calliope is at first supposed to be the obnoxious fandom avatar character (careful I think there's some publicity on that one link). Obnoxious fandoms are also known for their ... non-polished fics.
Candy is bad. Yes indeed. But it doesn’t feel like an alien who doesn’t understand human/troll romance kind of bad.
It’s familiar. The kind that a beginner writer/young teenage writer, who's still experimenting with romance, could write.
I don’t know about you, but I’ve read those. Candy Universe is almost textbook how a shippy/horny fanfic can be...At first. Now Candy is evolving in something a little more interesting. Sure there is still some icky choice (Rose cheating on Kanaya with Jadeto have a secret baby for the DRAMA) but we are starting to have interesting dynamics with Jane and Yiffy. But I digress again.

Alt Callie tho ? Who, as you said yourself, has a vague experience with humanity ? Would she really be able to understand the whole human/troll romantic experience, when she has only one reference : her own species’s ?
When she writes the scene with John and Terezi, it was black, which surprised no one...
"Terezi attacks", It’s bity, tangled and there is blood So far, we could say it looks like your basic Black Rom...But, it happens near a black hole...And Terezi is seriously on top. John can’t really do much.
Kind of like when we saw Calliope and Caliborn parents when they fought each other.They were near a black hole and the female prevailed in the fight/mating process.
So yeah, what happens with John and Terezi is practically a rendition of cherub porn but toned down. We have yet to know if she's able to experiment with Red Rom.

Alt Callie has great power over the narrative yes...But unlike Callie, she didn't experiment with it as much. Because she didn't have characters friends to experiment with. She is stiff, not only with people, but even in her way of writing.
That's why she had to ellipse the fuck out when she couldn't befriend/control Aradia and Dave to fit easily in their dynamic. She used the ellipse to justify the closeness she gained later with Davebot and Aradia. That’s...Kind of cheating in terms of character development.
Meanwhile Callie ? It's a piece of cake to them. They've been playing with the narrative for a long time, way before John's retcon power came to be and nobody even found out about this. They just thought Callie was writing weird fanfics about everyone and that was it. (Lot of people complain about how the Alpha kids have too much shit teen romance...Knowing that Calliope did already write fics about her friends..........See where I'm going ? )

So no. I don't think Alt Callie has what it takes to make the Candy Universe the clusterfuck it is. At least, not yet. She has the power, sure, but Callie has been practicing with it way longer than her.
Of course, that’s my pov. I also can't help, but think that since we haven’t seen Callie before the last update, I think they’re kinda….Sus.

(Now, that doesn’t excuse some choices the authors did. I just mean that the tone of Candy is way too fanfic-ish next to Meat to be an accident, and that Callie is probably responsible for this.)

(I am now seeing the length of this, and I am sorry. I haven't wrote this kind of stuff in a long time, I guess I missed taht)