Her injury was rather minor compared to what the subs and Bep went through. Also, as she wasn't a major character in this arc- or in general- she was safe as can be. She might roughed up a bit, but killed off? You don't kill off the bit characters.
Then frankly, maybe this comic doesn't suit your tastes. Yua has always had a focus on the combat, and a definite roster of favorites who get the limelight. Haruna is decidedly not on that list. You may find hisahiko's Haruna Weather more your speed, especially seeing as how she is the protagonist, or at least the main PoV. And the author is known for heartwarming content.
The whole point of this arc was that the aberrant Re-Class battleship was a massive threat- the first to do truly serious injury to the shipgirls of this base. Precisely because she used their own training and tactics against them, being part of Reiji's old squad. Keep in mind, we haven't even seen the Himes yet, let alone the Onis.
As for why no sexual porn? Because that is Comiket material, and yua actually does do H works- including some kancolle works. FWIW, one does involve Kongo, but it is separate from the Fleet Journal series. I imagine he wants to keep that work separate from Fleet Journal, which is story-oriented.
...Understood....Are you willing to give up this info?The Navy Research Department has already been notified.We authorize the shutdown of Operation F103.We'll contact you again regarding details of retrieving the sample and the report of this battle.Don't touch the samples and stand by.