"Why do you hate him?"
Translation:Proč ho nenávidíš?
Yes, it is the same word order, but the wrong word. JEHO is not 100% interchangeable with HO when it comes to placement in the sentence.
Placing the regular (long) form "jeho" in the second position (where "ho" would be perfectly fine) makes it clear that we are specifically interested in this "him", and that level of specific interest would mean that the reference to the "him" belongs to the right of "nenávidíš", not left.
This is certainly not easy to learn, but in the interest of not letting our users sound like goofs, we have to keep rejecting it.
I suggest reading the Tips & Notes for the Pronouns skill.
No, "ho" is a short form, it's always unstressed, therefore it must be in the second position.
The pronoun is stressed at the end (why is it him that you hate?) and for that we need the long form: "Proč nenávidíš jeho?"
Also please limit the number of exclamation marks to ONE. Otherwise you sound rude and people may not want to answer your questions.