While Ive only played episode 3 once, I did play it after this message so was on the look out for "Engrish". Now ill be honest, I didn't notice anything that stood out, but again I'm a brit, so the conversation flow seemed natural to me.A lot of "Engrish", even in some high quality VNs comes from the "flow" of conversation. Like it may technically be correct grammar and spelling but the actual conversations come off as awkward. I suspect the person who made the comment is American
That being said, it is full of what I'd call Britishisms, that is to say phrases or ways of phrasing that is normal to us, but could defenitely get lost in translation.
For example at the bar at the end our MC is decribed as "fit" now I don't know if this is the same in other English speaking countries, but here fit is used instead of hot, attractive, stunning, beautiful etc.
Obviously the proper use of that word is to do with athletics and health, so I could understand if a none English person reads this and thinks it's a little out of place to be said in a pub