Yes, she was really excellent in that show. Her acting, like her character, reallly was the center that held it all together.
Although I can’t say I remember that episode where she said “damn” (For sure I saw it), even now I can get how shocking it would be.
She imbued Edith with great dignity, a dignity that was never damaged even by her rather verbally abusive husband or somewhat condescending daughter. But she was never “hard”, like Alice Cramden was.
And I may be wrong about this, but my impression is that Meathead Mike was the sweetest of them all to Edith.