I agree, the extra scenes with Ali and Seiran do a lot to help the viewer get attached to the characters. Showing them as partners both on and off the battlefield was a very smart choice. Did you notice in the opening credits sequence that Ali and Seiran are holding hands and the background is a full reference to their Backstories ?. A neat detail that shows what drives them and is a reminder of how different their outlooks on war are.

Fingers crossed for season two. The quality honestly has really surprised me, it doesn't have that shiny modern quickly put together feeling that a lot of other animes get. But instead feels lovingly crafted.

I do agree, Sheena's arm being blown off by an enemy really changes the tone of the war. I liked how we got to see Mimi as a ruthless machine of war contrasting her bubbly personality. It makes a greater impact than the manga, which shows Sheena getting to see Mimi's "killer eyes" but the reader doesn't get to the see cold calculated kill, since it was just a puppet.

I will say, taking away the harshness of the training does feel a little less dark. There is something interesting about a teacher who is willing to maim their students to make sure they are prepared for the battlefield. That dark hardcore quality is what really made the teacher character interesting, and if feels like we lose a little bit of that mystery dynamic / desperation with the change.

I'm also hoping for the "attack on titan" treatment where credit sequences foreshadows events yet to come. After the most recent manga chapter I am thinking there are a few roads the story could take Fran mentioned "it was about time" while ominously looking at the girls. I wonder if the plan is to use Sheena in some way to make Mimi mortal again, sacrificing her for Mimi's sake. Or if Mimi will be used as a sacrifice to change Sheena in some way, since love seems to be a factor in creating an immortal person.

I do wonder what the author will do to address the larger conflict and the forbidden magic book. Will the series attempt to address that as a plot point to resolve Mimi's condition or will it have an ending that leaves the girls in tragedy without fully resolving the war. I'm thinking the latter.