I just wanted to give my condolences for your loss!
I have a male snow corn who greatly resembles the girl you lost. I know how difficult it can be to lose a loved pet. She was very clearly well-cared for, radiant and healthy in my eyes!
I *can* see why the vet would consider your snake to have been overweight, but she really wasn't terribly so. It is true that most people I know suggest feeding adult corns every other week. I usually follow this plan with most of my adult snakes. But females are often fed on a 7 day schedule in order to keep their weight up, especially if they are breeding. I would not worry about it too much, it seems like your girl passed form issues not related to her weight.
I doubt your other colubrids will experience any harm as a result of the 7 day schedule you had them on. It's extremely common for corns and other similar species to become obese in captivity, and while it has the potential to shorten their lifespan, I would say it usually doesn't.
1.0.0 Snow Corn Snake (Ziggy)
0.1.0 Pewter Corn Snake (Tarnish)
0.1.0 Albino Checkered Garter Snake (Zara)
1.0.0 Whitewater Rosy Boa 100% het Albino (Tikva)
0.0.1 Normal Kenyan Sand Boa (Needs a name!)
1.0.0 Cinnamon Ball Python (Trilobite)
1.0.0 Tiger Crested Gecko (Van der Waals)
0.0.1 Northern Blue Tongue Skink (Cobalt)
Whoop, didn't see this had new posts: I'm still sad that she's gone even though it's been ~five months now. But as mentioned I did change around my adult colubrid feeding schedule: they've been eating every 14 days with fine results (though I'm sure they're not totally happy about it lol) and no one else has been having issues that was in that same room with Vera. I'm thankful it was an isolated incident and hope that the info in this thread can give some insight to others.