For the TL, since he asked, here's the grammar/spelling issues I spotted
- P5: "The Shitennou who hold the power to rule over the water" Should be "holds", assuming I'm reading that sentence right
- P7: "The case of a salaryman who went to other world and was invited by the demon king!?" should be either "...went to Otherworld..." or "...went to the other world...". Really this sentence would flow better as "The case of a salaryman who was invited to another world by the demon king" or something to that effect
- P8: "Somehow I was going to appreciate..." should be something more like "Somehow I was starting to enjoy..."
- P8: "And then... when I regain consciousness" should be "And then... when I regained consciousness" since the sentence is past-tense
- P9: "What it's all this?" should be "What is all this?"
- P9: "Hell? Underworld?" should be "Hell? The Underworld?"
- P9: "Or is this the Limbo?" should be "Or is this Limbo?" (Yeah I know the rules for these are almost reversed relative to spanish, it's dumb)
- P9: "You're on my demon king's castle..." should be "You're in my demon king's castle..." or something to that effect. The sentence is a bit awkward in english.
- P9: "I was who summoned you here" is a bit awkward, perhaps use "I was the one who summoned you here." or "It was I who summoned you here" if you want him to sound a bit archaic
- P9: "You're one of the Shitennou the 'Overseas Resident Employee'" should have a comma between 'Shitennou' and 'the'
- P9: "Sounds just like an ordinary job!?" is an incomplete sentence.
- P9: "Why me a relocated salaryman?" should probably be "Why me? I'm just a relocated salaryman!" Or something. Those are two sentences in english.
- P10: "You were transferred to a factory abroad when you were already 5 years in the company" should maybe be "You were transferred to a factory abroad after five years at your company" or something similar
- P10: "That convince me" should be "That convinced me."
- P10: "Instead of being an improvement in my career, it would be something very negative for her" should be "Instead of being an improvement in my career, it would be something very negative for it"
- P11: "I don't have the right to force you to anything" should be "I don't have the right to force you to do anything", or "I don't have the right to force you or anything" if you want it to sound more casual
- P11: I assume 'speechlesshh' is intentional
- P12: "Since before we started half a year ago we already had these problems" is a bit backwards, try "We've had these problems since before we started, half a year ago" or something like that
- P12: "Machinery and qualified personnel are insufficient!" should probably be "Our machinery and qualified personnel are insufficient!"
- P12: "Again they're going to relocate me to another country" should be either "Again... they're going to relocate me to another country" or "They're going to relocate me to another country again"
- P12: "That was worth all my effort" should be "That was all my effort was worth"
- P12: "I am just a trash unable to do something." should be "I am just trash, unable to do anything."
- P12: "So please so as if we never had this conversation" should be "So please, act as if we never had this conversation" or "So please, just forget we ever had this conversation"
- P13: "Don't trust the bullshit's that fools said" should be something more like "Don't put trust in the bullshit words of fools!" or something like that
- P13: "I would never value someone who it's a fool" should be "I would never value someone who is a fool" or "I would never value a fool"
- P13: Continuing from the above, "Who does not put his eyes on the one who works hard without asking for recognition" isn't really a complete sentence, so there shouldn't be a period on the previous one
- P13: "That is a real idiot" is awkward, perhaps try "Such a person is the definition of an idiot" or "Such a person is truly an idiot"
- P13: "If possible, I want to bring out the maximum of your power" is strange, try "If possible, I want to bring out every bit of your power" or "If possible, I want to maximize your power"
- P13: "Neither your former bosses" should be either "Not your former bosses either" or "Neither can your former bosses". Both are a bit curt but sound better.
- P15: "I oppose that" should probably be "I oppose this", assuming she's referring to the situation and the offering
- P16: "I will decide a task..." should be either "I will decide upon a task..." or "I will construct a task..."
- P16: "And so they can change their opinion about you, okay?" is very strange in english, try continuing the sentence from the previous bubble with "and change their opinions about you, do you accept?"
- P17: "In that case, I'm going to verify that..." should probably be "In that case, I'll verify it..." or something more like that. 'That' is the wrong tense of word to use.
- P17: "Deadly!? That means I will inevitably die!?" sounds wrong, maybe do "Deadly!? That means she's trying to kill me!?"
- P18: "You always get carried away by your emotions, and that makes your vision cloud." sounds a bit strange, maybe try "You always let your emotions carry you away and cloud your judgement." Or maybe "You always let your judgement be ruled by your emotions."
- P18: "It would be better if you look closely" is weird, try "Calm yourself and look closely."
- P19: "The impact of a moment ago..." should be "The impact from a moment ago." Also, if no impact was actually made, use 'Attack' instead of 'impact'. Same for the rest of the dialogue using those terms
- P19: "This guy can use magic, or has some special ability." should be "Can this guy use magic, or does he have some special ability?"
- P20: "HOW DO YOU WANT ME TO ACCEPT THAT!!!" would sound better as "HOW DO YOU EXPECT ME TO ACCEPT THAT!!!?"
- P20: "How I would allow a human who has no skills or can use magic to be a shitennou." Should be "How could I allow a human who has no skills or magic be a shitennou?"
- P20: "The demon king's army it's full of evil beings" should be "The demon king's army is full of evil beings."
- P20: "Magical beings and demi-humans, will always seek to reach the top!" has an unneeded comma
- P20: "Deciding that he is a incompetent is something rushed" should be more like "Deciding that he is incompetent is being too hasty." or something like that. Also it would be "An incompetent", not "a incompetent"
- P21: "And Finally I will become a funny object!" I have no idea if this is bad translation or some kind of quirk. If it isn't meant to make no sense, try revising the translation.
- P21: Physical faculties should be physical abilities
- P21: "...I negotiate primarily ..." should be "...I negotiated primarily..." especially since the next sentence is past tense
- P21: "I found it difficult to negotiate, since being a different culture they had other rules." is weird, try "I found it difficult to negotiate since their culture had unfamiliar rules."
- P22: "NOW WE CAN GIVE YOU AN APPROPRIATE TEST FOR YOU" should either be "NOW WE CAN GIVE YOU AN APPROPRIATE TEST" or "NOW WE CAN GIVE APPROPRIATE TEST TO YOU". Putting 'you' twice makes the sentence sound strange.
Honestly it was perfectly intelligible but very obviously not translated by someone totally fluent in written english. I'd say get some american weeb to proofread it if you want to catch the smaller errors and make sure to watch your tenses. Also ensure you're using 'the' properly, as well as pronouns. Spanish nouns all have genders, but many english ones don't. Don't be afraid to use 'it' if you aren't talking about a living thing with a known gender.
Anyway, good job, looking forward to more of it.