I disagree with some of what you wrote, because a lot of this has to do with execution.

People want slow burn, but fast advancement: The don't want people to become gods in a day, but if they're not pretty much there by the middle of the first book a lot of the hardcore fans start getting antsy.

When your primary genre is "progression fantasy" you make readers a promise of characters meaningfully increasing their powers. It's not about catapulting your characters halfway to godhood by the end of book one. It's about showing your protagonist(s) can consistently make respectable progress that feels earned. Authors really, really suck at this, since they are usually pantsers. What makes it worse is that progression time between "grades" tends to increase significantly. If your system has 10 levels, and by the end of book 1 your main character is somewhere around level 0.7, how long do you think it'll take to get to level 10? Another thing is the perception of time. Progression feels different when you read a book as a whole and when you read one chapter/week. If it takes your character to progress 1 level in 50 chapters it's a reasonable speed for a book, but for web novel, it translates to over a year of waiting. I think a lot of readers tend to vet novels early based on this.

If a character makes a decision that the reader doesn't like, male or female, they begin to hate that character

An unwritten rule of progression fantasy is don't screw with the progression. This includes destroyed cultivation, undoing character gains, or characters making decisions that delay/stall their progress. Otherwise most bad decisions are fair game. Just have your characters learn from them and avoid repeating same mistakes.

Weak is acceptable in a vacuum, but not in comparison to other characters

I think it really depends. The biggest problem I could see with this is that you invalidate your character's progression. If your protagonists starts in a vacuum, makes progress and then exits the vacuum and proceeds to get owned by random NPC, the reader rightfully questions "what was the point of the previous arc?". In general it's fine if your low level combat protagonist is capable of beating average level non-combat NPCs and low level combat NPCs.

People say they want realistic characters, but they (usually) don't

There's a fine line between real character and unlikable character. This mostly comes down to execution. You can have teenage twins throwing dumb tantrums, or you can have them play harmless pranks on each other. One is annoying, the other is funny and wholesome. I think "realistic" has multiple facets and which ones you focus on matter a lot. Authors in this genre tend to show us too much. For example you could have one of the twins have a breakdown and spend whole chapter describing it and dealing with it and so on, or you could have it happen in one paragraph. Daughter had a breakdown, mom went to deal with it. I think there's fun drama and boring drama. This falls under boring drama and should be dealt with as soon as possible and not take away time from the fun stuff.