My issue with Edelgard is my biggest issue with three houses in general, is that Crimson Flower is very unfinished.
My gripe is that we never get to see how she would have handled Agartha. I can accept and enjoy a 'the ends justify the means' protagonist, especially in my 'political intrigue' story. I'm fine that she had a alliance with the Agarthans, they could have used that for interesting dynamics or just to LARP USA and USSR if they wanted to be lame. There is a lot of narrative space between the family intrigue with her and TWSITD and political assassinations and such, if they wanted to explore that. There are the implications of having Fodlan Jesus and Dubstep Devil on sort of the same team at times, with TWSITD having killed Jeralt, Edelgard's actions as the Flame Emperor are hardly looked at with any scrutiny. I'm ok with that in my historical fiction, but i'm not ok with that in my character driven narrative.
Instead, what we get is that Jeritza just sorta.... cleans it up for free offscreen. This removes the agency of dealing with the consequences of her own revolution from her, and that really denies her the chance to shine. She makes a deal with The Dubstep Devil, who then uses fantasy approved nukes, and all consequences of this are completely hand waved away because she defeated mother eugenics. It's a downright crime that she gets more characterization in the routes where she is the antagonist than the route where she is the main lord. I'm not asking for Sans Undertale to come judge my actions or anything, but please, anything.