Yeah, it's kind of designed intentionally to make you lose occasionally to find out what's coming and restart or newgame+.
Even when you know what to do, sometimes you just get shit luck on breed rolls or bad item drop rng. Getting the higher level spells on your better units is a fucking chore. Most the magic girls have shit breed stats. That's usually the point that fucks me over, trying to get some shamans with the best attack spells. Even keeping my mage line as pure as possible and avoid bad spells, it's still a crap shoot since everybody ends up with heal because of Anvil. If I have one gripe, it'd probably be that I wish the first girl you capture didn't have any spells. With the way passing on skills works, it can really suck.
I don't mind the difficulty though, it at least always gives you room to improve and still be challenged. Games like this usually quickly become far too easy and lose their appeal for me.