Thanks for playing! Chapter 3 has always been difficult to balance because it's an early defense map. It's very easy to turtle at the top of the map and survive with no problem, but the challenge comes from getting to the boss and his item without getting a unit overwhelmed by too many enemies at once.
I'm not sure why the prisoners on 5x didn't give you the item for saving them all but not talking to them. I even coded a conditional for that instance and made sure to test it. Were any of them rescued when the chapter ended? I'm not sure how the game handles rescued units when it calls CHECK_OTHERS. I should probably make all three of them un-rescueable because I got some feedback from another player that rescuing them and then trying to talk to them leads to a big mess and glitchiness as the game tries to move someone it can't even if they're alive.
Judith's got a 55% growth in strength, but I've definitely had her miss it a lot before and end the demo with only 8 str. Her offensive stats are kind of a coin flip honestly, but she's statted pretty similar to Hector, since his baseline was the original inspiration for her. I keep being surprised that we only gave her 20 base HP. We actually lowered the Mt on Sagaris after switching to FE8 because being able to output 35 damage against a level 1 cavalier was a little ridiculous. But we gave it +10 hit instead so even though it's the same Mt as an Iron Axe, now you can use it to offset her kind of low Skill. We might honestly give her a couple extra points of skill because I'm surprised at how low hit rates she's pulling even after getting some levels in.
Lily got a speed base buff after getting added to the Prologue to make her able to reliably double Soldiers, who actually had a speed base nerf recently. Those changes helped her be able to shine so much more since being able to hit for 8x2 instead of just 8 means she can chip to low damage for others early on or two round things she gets into a fight with. She's got really nice coin-flip offensive stats which is good for someone stuck with Bows only.
Nick's stats are garbage because they have to be since being able to output 13 or 13x2 magic damage against mostly 0 or 1 Res enemies would be a bit strong. But it does mean he's consistent in output at least and can be good for occasional chipping. He did get a full 20% boost to his Magic growth bringing it to 65% since the move to FE8, and combined with the higher staff xp gains if you choose to keep him around even after getting Beatrice you'll be rewarded with a unit that can deal a fair bit of damage and use special staves at high ranges. He'll never be as amazing as other units could be, but that's what happens with crutch prepromotes.
I'm glad Rowan turned out ok for you since we keep getting really bad ones in testing. We're thinking his problem is that even though he's supposed to be speedy, having a 60% growth in it, there are no real slow sword users in GBA FE. We even dropped Merc speed a little bit to make them more distinct from myrmidons but it hasn't really helped him out. Maybe he needs a bigger speed base or we need to drop merc speed even more. We'll have to see.
Having a bad Martin is unfortunate though since he keeps turning out incredibly for me and others. He's basically a knight on a horse sometimes, or Sain with defense, or Lowen with strength.
Clover's in that weird myrmidon place where she needs to get Strength to excel because her Saber isn't going to help her forever. The Killing Edge in chapter 5 helps, but she doesn't start at rank C, so you have to use her to get to that point first.
Kate might turn out better than her in the end, but she has a lower speed growth and will probably be focused as a utility unit for a while. The next thief isn't slated until probably...Chapter 15 or so. That said, she's meant to be the more fighting-capable thief, so if you choose to use her outside her thieving capabilities, she probably won't disappoint. I'd love to increase the amount of xp gained for stealing, and maybe even find a way to give small xp for using Lockpicks since when she's on utility duty she's not really gaining any xp otherwise.
Rose is meant to be the slightly bulkier of the pair between her and Fia, with high damage output too. But yes, she's slower by design since we've seen what she can do if she starts too fast and it's basically doubling the whole map for unmitigated dark damage. Beautiful to watch, but definitely not good for balance.
Fia will be more interesting to keep an eye on. She was moved all the way back from chapter 7 to chapter 2 with the story rewrites and had to get adjusted multiple times to fit her new join time. Having her around for chapter 3 is greatly beneficial. She's definitely meant to get a speedy mage though, almost myrmidon-esque in her stats and growths. I'm a little worried about her prospects as we go onlwards but once we get our expanded magic system added to the game she might fare a little better since she'll have access to a Saber-like tome of her own, and much later in the game access to tools like Thoron (killer anima) and Blizzard (FE5 sleeping included, though not siege, will require much testing and balance once added).
Lastly, June seems to turn out good no matter what. We didn't adjust her bases or growths any since the last demo, just her join time. She's a much speedier cav than Martin is, but at the cost of lower growths compared to him in most other places. That doesn't mean worse, just more balanced, such as having 30%s in both Def and Res compared to Martin's 40% def and 10% res.
Didn't mean for this to go on so long but I felt like responding in full. Glad you had fun with the demo!