I If i have in dom 1 forever burning, can i use in her several times to draw several cards? i explain, one forever 1-1 = 0, i draw, second forever 0-1=-1=0, draw second, and continue...

Each time a Forever Burning resolves successfully, a STR penalty is applied to a character. If that character's STR is 0, it's a valid trigger for Maegi Crone. So yes, you can do that.

I referred if i can do that in the same character, because i believe a penalty of str -1 when you count its str 0 and you can trigger crone.

Yes, you can do it even on the same character. The penalty has been applied successfully and the character's strength is 0.

It's one of those situations where the game mechanics and an "intuitive" reading of text seems different.

Because a character's effective STR can never be below 0, "after a character's STR is reduced to 0..." continues to be true when new STR modifiers are applied that take the calculated STR below 0.