The biggest autistic nomenclature tantrum was about renaming Derpy "Muffins."
https://encyclopediadramatica.se/Derpy_Hooves
Somehow, people can't grasp that making fun of exceptional individuals is not exactly politically correct and that maybe a show for kids is going to shy away from that.
Ahh showing my powerlevel but gotta correct this one. (give me all your autism ratings one and all!)
For one, she's not got an "Official" name at all now. Build A Bear called her muffins, the VA credit for Episode 100 where she's protagonist names her "Bubbles" - but far as Hasbro is concerned. The gray mare with cross eyes will never have a set name. (On toy packaging her name is usually just an muffin icon)
Derpy was originally called Derpy, even by the show crew and staff internally. It was never intended as a slur, just when she was originally an in-joke insert, someone nicknamed her Derpy because of her cross-eyes and it stuck (I've only ever known the term be used when someones being clumsy personally, eh)
She was the fandom mascot of sorts during season 1. Nobody really made fun of her outside drawing her doing slightly silly things (because lets be honest, most of the Brony fandom is autistic anyway, so most of them just saw themselves in her). The show crew then during season 2 started to animate some of the background/filler ponies and Derpy became more of a visible character. Mid-season 2 they did actually release an episode where she spoke for the first time.
In the originally aired episode, she's called by name as "Derpy" by Rainbow Dash. The VA for the character also didn't realise this character was notable to the fanbase, so she tried to give them a male voice. Unfortunately the result is the original episode script and VA performance made her sound kind of exceptional.
The likes of Cuteo then started calling foul after the episode, saying that suddenly this name that had unofficially been used for this character a year prior was ableist. It was pretty much your usual SJW crusade of today. *Actual* Disabled fans of the show were upset because they related to the cross-eyed pony more than anything else. So another case of speaking for a group that doesn't even want the thing your calling for.
Hasbro freaked out and then suddenly removed tons of merch that already had Derpy on it from sale, pulled the episode where she spoke, and then rewrote, redubbed and edited the original scene she's in. Removing the name of the character ect. Hasbro also set an unwritten rule of thumb that this pony would never ever have an official name. They then stopped having her appear for a few seasons, before having her re-introduced after things died down, and she became the protagonist of the 100th episode.
As for Sweetie Drops and Heartstrings. During the earlier seasons of the show, Hasbro's Toy Dept and the Show were not really working together much. Fandom had sort of named them, but I think people were just like "it's kinda weird that they have totally different names..." - once Hasbro became more aware of the shows cult success, they merged the show-canon names in.
Also DJ Pon-3 was absolutely not the fans choice of name. Vinyl Scratch was the preferred name, but DJ Pon-3 worked better in the orignal Hub promo where she first got named. She basically has both names officially anyway.
