It's not legal unless the person had the rights to begin with. It may be legal for a clean room reimplementation, but not a decompilation project like this. iD/Apogee can totally request a takedown, so I wouldn't recommend republishing that...
Based on what? Afaik decompilation is a grey area and projects that enforce clean-room design do it to stay out of this grey area.
I'm not a lawyer. I'm reasonably sure I'm right so the above is good enough for discussion, but if you need legal advice see a lawyer.
Not quite true. You and I both own the copyright to your translation. Neither of us can publish it without the other's permission.