1. Why would mildly annoying 4 people be justification enough to create a whole world as a kind of "hell"?

It's not like they're spending money on maintaining it lmao, hell in a later episode of season 2 they dismantle the whole thing like its a toy. There was little to investment there besides Michael's time and effort.

2. How is an ancient immortal being not smarter than humans?

He's vastly smarter than every human, it's mentioned multiple times that he knows basically everything there is to know about the universe.

3. Chidi is in hell because he was indecisive? Wow, ok.

Which made the life of everyone around him miserable. Just because you study ethics doesn't make you a good person.

4. Tahani is in hell because she didn't really care about the people she was helping? What?

She was a self-absorbed bitch. Sounds like easy hell material to me.

5. Chidi and Tahani are in the same place like Jason and Eleanor? Why?

There are only two places: good and bad. Since the good place is clearly very selective, naturally everyone that doesn't make the cut goes to the same place. Pretty obvious here yet again.

6. Why are hundreds of ancient immortal beings interested in spending time with these 4 characters, under the direction of a seemingly incompetent ancient immortal being?

Because being immortal would get boring and it's pretty clear they all are in it because its new and fun.

7. Why is there a neutral computer being in hell, aside from being a "funny character" whose punchline is "appearing suddenly"?

This is explained in a flashback in season 2. Michael stole Janet from the actual good place.

8. What happened with the romantic angle between Janet and Jason?

This is also explained in abundant clarity given the Janet was "killed" and reset, and Jason was "killed" and reset hundreds of times starting with the ending of season 1. They completely forgot about each other. Then at the end of season 2, which you clearly did not get that far, Janet remembers and professes her love to Jason.

9. If there is an in between place where the coke lady is, why couldn't have Chidi and Tahani gone there, aside from the fact there wouldn't be a show then.

Because the coke lady did enough good in her life to be considered better than Tahani and Chidi? Man that was so hard to explain.

10. Why is the coke lady in the middle place, she's more terrible than Eleanor.

What makes her terrible? That she likes cocaine and masturbating? Didn't the show explain that she started some company or charity that did some amazing things for the world?

11. Why does Janet need to be rebooted every time they erase the 4 people's memory?

This was not even happening as far as I'm aware.

12. Why does she need to be rebooted by pressing a button in a metaphysical space?

Do you have a lot of personal experience with the logistics of living a metaphysical space? How can you call this a plot hole when we're talking about a ****ing science fiction comedy

13. Why is there a fail safe mechanism for her rebooting? Aside from a few jokes.

Jokes that were undeniably fantastic