Its a good question though to be honest theres not much in the way of easy answers.
The plain fact is that Donna Troy was created to be a sidekick of Wonder Womans in the Teen Titans comic without ever having actually interacted with her. And she wasn't even given the name of Donna until a good seven years after she was added to the Teen Titans.
Donna is in a difficult position because she was created to be part of the former sidekick club but in reality she was a newbie just like Cyborg and Starfire. Yes there was a Wonder Girl before her, but for obvious reasons she couldn't really be considered Dianas sidekick. And even when Donna was established to be her own character she rarely interacted with Wonder Woman. By my count, Wonder Woman and Donna spoke once for a single panel in the first issue of Teen Titans. Spoke once indirectly in the issue where the Teen Titans swore to never use powers or wear costumes ever again. Briefly interacted in that one issue of Wonder Woman where Donna was kidnapped by Doctor Cyber. Then nothing until the storyline where Wonder Girl gets married.
Then its a good twelve years before the two ever interact because post crisis led to writers retconning Wonder Girl and Wonder Woman having anything to do with one another. By which point they were redoing Donnas origin again because they had given her an origin to seperate her from Diana and then tried making up a new one to make them connected again.
The problem is that Donna was created for the Titans and in all the years she has existed very little has ever actually been done with her. In theory she is tied to Wonder Woman so she didn't need a deep backstory like Starfires, Ravens, and Cyborgs. She didn't need to be given personal villains or a complex mythos because in theory she wasn't original to the Teen Titans so she could just develop outside of the book like Robin and Kid Flash. Except that since she never was in Wonder Woman and only appeared in Teen Titans she was basically regulated to lending to other characters stories.
The few stories she has had over the years was a romantic relationship with *insert titan here*, an arc in which she married the authors self insert because he had a crush on Wonder Girl and had a kid with her. An arc where she was left reeling from the fallout of her husband and kid dying. An arc where she went and became a darkstar for about a year. A brief bit where she was Wonder Woman for all of five minutes. And a brief blink and youll miss it moment where she was in the Justice League.
Also Donna is badly held back by her greatest weakness. The fact that theres nothing to make her distinct from Wonder Woman.
Dicks stands apart from Batman because hes always been dressed differently and is considered the brighter cheerier counterpart to Batman.
Kid Flash and Speedy look radically different from their counterparts.
Aqualad would go on to get a new set of powers that Aquaman did not possess.
Donna however? Appearance wise she was based on the original Wonder Girl who WAS Diana and even when she would get costumes which were radically different from Dianas it still was hard to tell them apart since they had the same face. A fact that later writers would lean into, going and just straight up making Donna a literal copy of Diana.
In terms of personality writers have trouble being consistent and will either try to make her like Diana or will focus heavily on romantic sub plots with her and push her as being the emotional one of the group whose personality trait is being the one other characters can bounce off of in order to develop their own characters.
In terms of powers she not only has all the exact same abilities as Wonder Woman but she fights exactly like her. Wonder Woman has a lasso and bracelets? So does Donna! Diana stops using the lasso? So does Donna! Wonder Woman starts using a sword and shield? Watch out, Donna now has an identical sword and shield!
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Writers are in love with the idea of just making Donna a cheap clone of Wonder Womans to the point that they hesitate to do anything with Donna that would allow her to stand on her own. Sure there have been some attempts. That stint where she was a member of the Dark Stars and had a power suit which basically made her a spacecop with Starfire powers
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Or Finch's effort to make her a golem with regeneration powers, the power to see the past/present/future of anyone she meets and a magical pegasus as her steed.
But such attempts are quickly discarded in order to make her more generic creating the true problem for Donna.
When you have someone who is exactly like Wonder Woman and has all the same abilities, physical appearance, and personality as Wonder Woman, why wouldn't you just use Wonder Woman? What benefit is there in using Donna Troy when theres nothing that makes her stand apart?
Artemis, and Cassie have the benifit of looking completly different and having personalities that stand apart from Diana.
Plus they all more or less fight completly differently from Diana. This translates to writers benifiting from using them in situations that they wouldn't necesarily use Wonder Woman in.
So thats a major hurdle that needs to be cleared first.