I just finished the demo, and I thought I'd give you my thoughts on it.
Graphics: Sawyer's battle sprite is okay, while Owen's is sorely lacking in motion (same for his map sprite). As for portraits, Owen's hair looks kinda weird to me, along with the front of Sawyer's hair and his clothes, and Eli's hair, but everyone else is okay. The maps are okay, but they have some errors.
Gameplay: Map design is good, though there's some enemies I wish just charged after some turns instead of just staying there waiting to be aggroed. I also didn't like how Sawyer and Owen have to play a whole chapter with only their prf tomes and no mages or horsies in sight. There wasn't any unit I felt was particularly strong or weak, though Owen got kinda RNG screwed (most of his level ups were just 1 or 2 stats).
[spoiler=Story]First off, the dialogue itself was great. It was fun and unique. I found the story to be pretty bad though. Gonna go through it chapter by chapter (though I occasionally segue into general stuff. Also, my memory's a bit fuzzy about the story, so take this with a grain of salt). 1-1: This was okay, pretty good intro to the characters. Though, I'm not sure why Fortuita sent 2 nobles and their retainers on scout duty. 1-2: Kalvesta proves herself to be a terrible queen right from the get-go, allowing the enemy country to walk over her, leaving Nikolas to die, and ignoring her advisor (whose job is to, y'know, give advice) by saying he doesn't understand anything (it's the job of an advisor to understand the intricacies of their chosen fields of research more than their lord, so their lords can focus on their lordly duties while trusting their advisors to give them well-educated information, opinions and choices on the matters at hand). I don't know if Kalvesta has some secret reason for avoiding a war with Arynden at all costs, but even if she does it's a terrible idea to not even explain it to Seneca (unless she can't do that either, in which case you're likely forcing the story to go this way against all common sense). Also I think this scene should have happened at the end of 1-1, to give the idea that Seneca's coup didn't just happen overnight.
Which brings me to my next point: Seneca's coup does just happen overnight. He seems to have been in a shaky but otherwise somewhat okay relationship with Kal before the scene, yet he's out for her blood by the end of it, and he even gets blondie (forgot his name) to convince everyone to rebel in a single scene (even if he's got a silver tongue, that's too much). A suggestion to fix this would be to say Seneca was laying the seeds of rebellion everywhere beforehand, as a backup plan if Kal didn't change her ways; Everything's mostly ready by the time he decides enough is enough, and he just needs a month or 2 to put it all into motion (btw, you should add some timeskips between chapters and even between some scenes, I got the impression that the first 4 chapters happened in a day or 2).
On a less important note I think Belle should easily be able to find a good sparring partner without having to go looking around some random village. Maybe have it be that Kal doesn't want her to fight and forbids anyone from training her or sparring with her, so she's gotta do it in secret? Also, Nero overhearing Seneca and blondie is rather pointless, since he never tries to tell anyone (except the girl that was with him in 1-4) and in the end nothing comes out of it).
I'm also going to mention that I was rooting for Seneca through the entire hack.
The starting scene was a bit on the short side. Maybe you could add a short villain interlude for Arynden beforehand? Also, I don't think the ending scene conveyed just how bad the situation was for the fort too well. You could have some scenes (2, maybe 3) mid chapter where Nikolas' forces take heavy casualties, and you could also show a big-ish green force in the first scene, then show a much smaller force at the end.
Another thing this hack could do with is a world map. They're really useful for visualizing where everything is, and world map events can be used to inform the player about many things, such as the current political situation, or who those 2 nobles with Seneca were (I don't think they were even named). You could make a world map with this, or you could at least do some faux map events, like the narration at the start.
Again, Seneca's coup is going too fast.
Kal died too early. There really wasn't much time to get to know her. Seneca's temper could instead be shown by having him almost kill her before getting reined back by his co-conspirators.
The 3 villagers that were with blondie at the start were too few. Maybe add 3-6 more villagers so it looks more like a mob?
I feel like Belle didn't react appropriately to the news of her mom's death. She also had no reason to charge towards the castle instead of running away (well, it could've been out of anger, but Oona and Charles didn't try to stop her). And I feel Seneca should've come out to try and reason with her before sending out the... was that the royal guard?
Owen and Sawyer's adventures feel like a side-story at times. The constant jokes, as good as they are, don't help, and neither do the bandit chapters.
The starting scene, again, was rather short and could do with a villain interlude (this time for Seneca and co) beforehand.
1-6 and 1-7:
They were okay, I guess. 1-7 was a bandit chapter and I think 1-6 had some undeserved Kal praise but otherwise they were okay?
Belle comes off as completely irrational when arguing with Regina, but I think that's on purpose?
Owen talks about how he was a former friend of Regina's, and they had a falling out and all, yet they don't even have a conversation and she just dies. That felt kinda pointless.
I think it's mentioned here that Seneca lost the support of the people. That's kinda weird, since he had a good public image (can't get better than "the only one doing anything to save the country from the evil invaders"), was reinforcing the border like everyone wanted, and his co-conspirators were leading 3-person mobs last time we saw them (actually, I find it weird that there wasn't a single house or village that had someone that was pro-Seneca and against the Kal and Belle).
Belle saying Kal would have wanted her to start a civil war in Fortuita's time of need goes against all of Kal's established character, yet Oona just goes along with it?
Also, the status menu objective in 1-5 says defeat Reece.