If English is your fourth, you're doing an amazing job.
There were a few screens where I wasn't sure what was being said, but overall, it's more about individual word choices I'd tweak as a native English speaker. For example, "a sense of anticipation tinged the air" would probably be "a sense of anticipation hung in the air." Also, cops tend to speak a certain way, a lot of technical/military language with jaded street-slang. Instead of "Just stay outside and only act if something goes wrong," they might say something like "I got this, stay put. Entry is authorized only if you observe firearms." (Don't use that, it'd sound out of character by itself.)
Don't people ever volunteer to do stuff like editing for free? Especially someone wanting to get into development. I turn down requests to do work for free all the time in my day job, but see the stuff on this site being more of a hobby.
Anyway, I don't think any of the issues are game-breaking. You might consider finishing most or all of the game first and then re-releasing with a rewrite after you find a volunteer or cheap editor/writer. That'd give people an excuse to replay!