I am grateful to see this translated, don't get me wrong. But if you're asking for feedback...
1) Don't put English SFX over JP SFX. It's ugly, it overcrowds the page, and it obscures the actual art and composition in a lot of places. Either wholly redraw the SFX or simply add a note. This inbetween is grotesquely unprofessional and looks far worse than either of your other options.
2) The TL is stilted. Far too many sentences have an unnatural structure, or bizarre wording choices. An example from chapter 12:
ORIGINAL
Listen well. All you've done up to now
...was never a battle.
Suicide.
Extermination.
That isn't a battle.
But now, to protect what's important to you from a powerful enemy...
You took up your sword.
This is a battle you must fight.
Because it can not be lost.
I'm going to assume the gist of the TL is correct here, or at least that what I can unambigously interpret is (and I'm not sure it is correct, but that's beyond my expertise). There are a couple of ways you could render this into more natural, less ambiguous prose—all while keeping some of the structure or cadence intact. I'll give one:
SUGGESTION
Listen well. You haven't fought a single real battle...
until now.
Suicide attempts?
Unilateral slaughters?
Those aren't real battles.
But when you wield your sword against a dangerous enemy
so you can protect what matters to you?
That's a real battle, because you must fight
lest you lose something dear.
There are several odd ambiguities in the original that I was forced to remove:
- "Suicide" is ambiguous between enemies throwing themselves at Firo and Firo throwing himself into battle hoping to die. I chose the latter, since it made more sense in context
-"It" in "it can not be lost" lacks a clear antecedent; it could be either the battle, or the important thing (taisetsu na mono, i'm guessing). I assumed the latter.
Probably more I could say, but I'm tired, I've looked this over way too many times, and it's getting late.
Here are a few other lines from chapter 13, and what I'd consider more natural renderings in context:
1.
ORIGINAL
Who knew bringing down that king-class fella would be so bountiful?
SUGGESTION
Who'd have thought that king-class fella would drop so much loot?
2.
ORIGINAL
I never thought we'd have such a bad outcome in the relic palace's sanctum...
SUGGESTIONS
I never imagined we'd leave the sanctum of the relic palace empty-handed....
I'd figured we'd at least get something from the sanctum of the relic palace...
This isn't unreadable, but it's clunky. A reword helps a bit and keeps the meaning. Both "relic palace's sanctum" and "sanctum of the relic palace" are a mouthful, though. It's hard to make it flow well.
3.
ORIGINAL
Being told to ignore those boxes by the treasure-crazed Seren...
I figured something like that was the case.
SUGGESTION
Seren is obsessed with treasure, but she told us to ignore those chests.
So I figured something was up.
Epithets like "the treasure-crazed Seren" just aren't used in everyday English. They're primarily associated with poetry, especially stuff like Homer. Avoiding them is a good policy.
Really, I would just try to recruit a good editor. Mizukami Satoshi is a pretty popular mangaka, as it goes. You probably won't have -that- hard a time getting someone to vet your prose.