Regarding the Tier 7 durability feats of the Eds and Jonny 2x4, I don't know what to make of them. Have those calcs been properly evaluated?
I actually favour the low end of the house explosion calc. It's consistent with a bunch of other 9-A feats from the Ed boys throughout the series; Such as Ed picking up an entire house and dropping it on Edd's head (who was in pain but completely conscious from the event), making small craters in the ground due to falling from great heights, surviving the destruction of Jimmy's house due to some jawbreaker bomb gadget thing Edd made (the Eds were at the epicentre of the explosion).
Edd is the physically weakest of the trio and even he has 9-A durability feats. Eddy is capable of easily harming him - such as when he once kicked Edd across the cul-de-sac and painfully bent Edd's spine with that kick. So Eddy should get 9-A for his Attack Potency.
Kevi is one of the physically strongest characters in the series. In the episode where Ed lost the key to his house, he was seen fighting evenly against
the son of a shepherd and has consistently been shown as capable of effortlessly beating the shit out of all of the Eds. So he should scale to both Ed and Rolf.
The Kanker sisters of course also scale to Ed, Kevin, and Rolf. The Eds, Kevin, and Rolf are all afraid of the Kankers and those girls have consistently been portrayed as the physically strongest characters in the series.
Summary
Eddy's AP should scale to whatever durability is agreed on for Edd.
Kevin should scale to Rolf.
Ed, Kevin, Rolf should get AP ratings equal to whatever durability is agreed on for all of the Ed boys.