I still fail to see how dicking around on the frontline brings him closer to his original objective. What he needs is a covert infiltration, unless I somehow missed the point and he murders them so hard they give up the goods.
The idea is that he needs to be part of the military to 'allow' him to fight/kill the invaders, as otherwise he's a civilian adventurer and that'll cause problems (for him) later on (civilians potentially killing nobles or their people etc). It's true though that he could just go rogue and save Ana without that.
He needed to scam the King to get sent to the front because student volunteers are mostly used behind the lines (pg.18 "supporting the army from the rear" and pg.21 "assigned tasks like publicity, transporting supplies, or providing aid").
It's ALSO a good way to get his achievements during the war recognised by the kingdom, which helps his goal of wifeing up Ana with her dads permission.
In most cases bullpup are extremely flawed. There necessary some workarounds so many really dislike it.
That's a gross exaggeration. AFAIK the main issues people have are squishy trigger pull, reloading and lack of adjustable stock.
The first is true, but hardly big issue, especially if it's military issue and not weekend target shooter who wants everything perfect. Soldiers use what they're given and get used to it.
Reloading is just what you're used to, though it's true most shooters will likely be more used to the magazine in front of the trigger.
Adjustable stock is doable in a bullpup (though to be fair, I've not seen it done), but there's also a ton of non-bullpups without adjustable stocks too.
Oh, also the lack of easy ambidexterity when shooting. Unlike many AR or AK style rifles, you generally can't just swap shoulders, and the few you can, you'll end up with brass flying right by your nose within tickling distance.
I wouldn't consider any of the above to be an 'extreme flaw', That said, I'd mostly consider myself a vaguely casual enthusiast of military gear, and not a shooter/collector or gun enthusiast or whatever. So take this with a grain of salt. I do know though, that, like with opinions about the F-35, people can have
very strong opinions one way or the other about bullpups.