that;

CH:20
It was a dislike so little just -- every imputed fault was so magnified by fancy, that she never saw Jane Fairfax the first time after any considerable absence, without feeling that she had injured her;

Emma’s behaviour IMO has to be judged from where it’s coming.

It seems to be common knowledge among friends and family that Emma ‘senses’ things and more often than not these sensed/guessed things come true.
CH:5 Mr Knightley says,
I do not pretend to Emma's genius for foretelling and guessing.

Emma’s given to flights of fancy and imagination. A man rescuing a woman from, according to her, ‘certain death is thick with possibilities for such a mind. It will wander into all sorts of romantic notions about the said woman, and the very novelish angle of her falling in love with him. She should of course learn to subject these flights of fancy to understanding as Mr Knightley says in CH:5

-She will never submit to[ ……] a subjection of the fancy to the understanding.

Mr Knightley brings up Emma’s fanciful thinking again in CH:12
If you were as much guided by nature in your estimate of men and women, and as little under the power of fancy and whim in your dealings with them

**I have to say, Mr Knightley knows Emma best and why she says or does certain things.**

Emma and the others in Highbury seem to speak their mind, and Emma’s lack of tact is more a sign of her small town mind than anything else.
She has something in mind and she needs to ask and she does.

These are not excuses for Emma’s behavior but an explanation for them as I see it. Personally I see all these flaws as something not deep inside her. To me they seem normal enough.