Ryu got hit with a dismantle from the same finger level Sukuna, and tanked it with much less damage. Unlike Mahoraga who fell to his knees, Ryu just staggered back. Or if that's too charitable for you, you could even argue they took the same amount of damage which still puts them both above three fingers of sukuna. Either way, that puts them both above 3F at the bare minimum.
And following your idea of CE level equating to fingers (which isn't the best train of logic since Sukuna even at one finger could walk all over a curse who was at One Finger, and the Finger Bearer that Megumi fought after was stronger than the one beforehand showing how the fingers individual strength is growing as time goes on as said within the series), Yuta isn't told to jump in till Sukuna is at half which would be 10F, and Sukuna puts himself at Yuta's level when they start fighting which has Yuta able to damage this same Sukuna with his hits, even tearing off limbs and such.
To say these characters are below 3f is crazy