It's nuanced in the way I think you're missing.
Wanda didn't know she was forcing people into roles. At some point she started to realize, but when asked she denied it vehemently, and even at the end she didn't truly realize how far it went. You can see this clearly when Agatha breaks the control on them (which mind you, she refrained from doing for...how long?). She says how it's impossible that they shared her pain, that she didn't do that, etc. Once she started to realize near the end, she did think they were genuinely happy at least. Keep in mind she never saw how far the hex went and how people outside of her close range just kinda 404'ed to stand in place. She didn't know that. Again, the entire point even Agatha pointed out that Wanda has no idea what she's doing with her power.
Compare that to when Agatha was chained up and being told WHY she was being punished by the Coven. For forbidden magic. Which she just snidely commented back on, and only started to beg after.
You're oddly giving Agatha the benefit of the doubt in the regard of her crime, yet missing that everything Wanda did was genuinely unintentional. She didn't realize how much pain everyone was in, she didn't realize how much it hurt them. Does it justify her actions and make her innocent? No.
Does it make more sense that she was genuinely suffering from god knows how much mental pain and suffering from severe depression? Yes.
Compared to Agatha, who willingly chose to delve into forbidden magic as presented to us.
Also your idea that "it wasn't a trial", Agatha literally admitted they were right immediately basically. Like, they knew she did it. She said she did it.
To tack this on a bit later, this really just wraps all the way back into what I said earlier.
Wanda summed it all up.
The difference between her and Agatha was Agatha did it all on purpose. Wanda didn't. It was a tragic accident.