This series needs a different proofreader. The current one obviously isn't doing his job.
At least that's what I'm assuming based on the fact that the same proofreader is doing both translation and proofreading for Tsui no Taimashi, with vastly superior quality too.
I mean:
"I try to keep these places away" -> "I try to stay away from these places"
"We don't come to play" -> "We didn't come to play"
"It is difficult to look mountains sweetly" -> "Don't take mountains lightly", maybe?
"If you have a car" -> "If you had a car"
"What sweetens the mountain is time and effort" -> Sorry, what?
"It's just the goal" -> "Almost there"
"there are an unusually large number of" -> "there's an unusually large number of"
"I didn't needed to hear" -> "I didn't need to hear"
"Did it start 6 months ago that the people who passed through the tunnel got sick?" -> "Was it 6 months ago when people passing through the tunnel started getting sick?"
"Didn't you just ignored the laws of physics at that time?" -> "Did you just ignore the laws of physics?"
"It's hard to think that" -> "I don't think so"
"It shouldn't have been that long since I possessed her" -> Makes no sense in the context of this story. When did Grudge ever possess "Xiao"?
"Is recent" -> Should be either "Recent" if it's meant to finish "This is...", or "It's recent".
"It was more than one accident" -> "It wasn't just an accident"
"It's funny" -> "That's funny"
You can't seriously expect me to believe that someone who can actually write English actually ever proofread this shit, can you?
There are more issues, too, albeit very minor ones. These are just the most obvious and distracting ones.