One day,
A deliveryman
↓
A→a
追い込む？
thumping, beeting heart
↓
, beetingトル
ドクドクあばれまわる心臓→thumping heart jumping around ？
There seemed to be others.
The trashman left the trash pile.
↓
others→other living things
trash pile→trash area または dump yard
The monsters went around everywhere and their pockets full of treats.
pockets full of→pockets became full with
（前出はit was full of monsters）
treats→candy
across town→across the town
You're gonna get your smell on me→Your smell...
That was when it happened→That was when he heard the voice
Why don't you…→Why do you not…
my dirty pants are mixed in there→my trashed underwear is included in your body
疲れたのでここまでにしておきます。
やっぱりネイティブが訳さないとダメだと思います。
日英翻訳の基本は、英語ネイティブが訳して日本人がチェックする、です。