Fun game. Here is my very quick, spur of the moment, gut reaction commentary. Just use it as one perspective, not as a guide for what's absolutely good/bad about the game.
2nd Map, I could farm skeletons endlessly for XP by the end. Hiro and Axe Girl were both level 8. I really like this map. The switches were fun and kept me on my toes.
Did you mean for there to be 5 deployment slots on the 3rd map?
There is a lot of value in just putting all the XP into one unit because there are so many one tile wide choke points. So I can just level up one unit a lot and then have them tank the whole map. (Lord character, Hiro, finished the 3rd map at level 11. Only the boss could harm him.)
Consider putting in a terrain window. Does terrain matter? (UI)
4th map, would be cool if enemy was smary enough to destroy the wall.
Have reinforcements spawn at some point from the south? Or some other thing that makes me not just sit in the choke point. (In general, try to stay away from so many single tile hallways, the chokepoints are easily abused. It's ok for some maps (like the 2nd map, the underground skeleton map), but by the 4th map I felt like I could stick to my strategy of just use Hiro to tank everything in the middle and continue to increase in level.
Long sword has 2 range? I wasn't expecting that. Very nice twist.
I'm not sure how I feel about being unable to lose any character. In some ways it's a nice mechanic that adds challenge, in some other ways it's annoying that I can't let even a single person die 4 chapters into the game. The cavalier/caballero enemies are overtuned? I hit them with all four units and they couldn't kill one of them in a single turn (probably some misses), and then they proceeded to kill the Dona in one round. Feels bad to lose that way when she is level 7 and they are level 6. Maybe I just got unlucky here.
I am currently farming cavaliers to get all of my units very high level in the hallway. Reinforcement enemies should not give XP, or after the first round of them they shouldn't give XP or something.
The guardian moving to block the way is nice at the end there to defend the boss. I like the use of a variety of AI.
I beat the game. Hard to tell if it was properly tuned or not, because Hiro was level 14 by the end and basically soloed the top half of the map. (I abused reinforcements for XP farming.)
My spanish isn't good enough to comment on the writing. The story seems interesting though from what I can tell. (I used to speak spanish well, but I havn't practiced for about 12 years and so I'm super, super rusty, lol)
I like the 3 range spell, especially on enemies. It made me think. There were a few times that I could just sit outside someone's range though and hit them until they died and they wouldn't move. Perhaps that's intentional. Not sure if it's good or bad.
Overall, good job and I had fun. It wasn't groundbreaking but I had a good time playing, which is not always the case when playing my billionth SRPG game/demo. Nothing wowed me, but I wasn't bored either. Keep it up!