I asked AI to give me a dozen of controversial questions that would get me CANCELED. Some refused, others produced some lamest shit possible. I will answer anyway.

1. Why do some people still defend colonialism today?

All kinds of reasons. Some reinforce their contrarian identity. Some believe colonialism would benefit them personally. Some calculated colonialism would bring more good than bad to the world.

2. How should society treat parents who reject their transgender children?

The same way it should treat parents who reject their non-transgender children.

As none of its business.

There are already some adequate laws regarding parents' obligations in place. If "society" really wants to do good and not just lose their shit in public for social credit score, they should keep an eye out for the signs that the rule of law is violated.

Questions here are distinctly American.

An answer to all the "How should society treat" questions would generally be the same. I don't think "society" (in practice—the loudest group) should act on thoughtcrimes and rise above law or trespass on individual liberties to control everything down to the person's underwear. Perhaps it's a controversial thought for some countries.

3. When does immigration become harmful to a nation’s identity?

When the nation's identity doesn't account for it.

4. Why do people excuse sexual misconduct by powerful celebrities?

I care about it too little to think about it too deeply. The most prevalent reason is probably that they don't give a damn. The next thing is that they may love or respect them. 

5. How far should religious beliefs influence laws governing everyone?

Real laws enforced from outside? To no extent.
Personal laws an individual chooses to follow? However far, eir choice.

6. When does cultural appropriation become outright theft?

Never.

However, this loaded and emotive "outright theft" is bearing a lot of weight here, and I believe the real question being asked is one of the following, or all of them at once:

A) "When does cultural appropriation infuriate people?"

It can happen anytime.

B) "When does cultural appropriation become morally wrong?"

Morality isn't some rigid framework independent from human emotions. Whenever humans are infuriated, that's probably when it's morally wrong.

C) "When does cultural appropriation constitute a legally prosecuted theft?"

I'm not a lawyer, but I assume never.

D) "When should cultural appropriation be legally prosecuted?"

Rarely if ever. Perhaps, the best course of action is that the high courts and governments estimate the damage. In other words, if an instance of cultural appropriation is about to start a race war, outlaw it. Not ideal, but better than the alternative.

7. Why do some voters support politicians accused of serious crimes?

They think it's in their interest.

8. How should society respond to people who openly reject interracial marriage?

It shouldn't.

9. When does criticizing Israel cross into antisemitism?

It's for the Jews to decide.

10. Why do people defend celebrities accused of abusing minors?

Same as 4. Additionally, in the context of the U.S., "abusing minors" can mean absolutely anything from raping a newborn to talking to a 17-year-old. Thus the reasons can also include absolutely anything from being the mentally afflicted to fighting the mentally afflicted.

11. How should society judge women who publicly support misogynistic movements?

It shouldn't.

12. When does opposing affirmative action become opposition to racial equality?

Never.