Jag-Stang bridges are 7.16" Fretboard radius, same as the vintage Mustang.
Adjust-O-Matic guitars are all 9.5" Radius. I don't think Fender used a 12" Radius on the Cobain guitars, or any for that matter.
Actually, an interesting fact about the Cobain guitars - both Kurt's actual guitars and the signature models, is the string height adjustment. When Kurt's guitars were setup for the Gotoh Tune-O-Matic, I'm pretty sure Ernie Bailey might have filed the saddles so that it matches the radius. Most of those gotoh tune-o-matics come without slots cut in the saddles - I know because I've installed quite a few on Harmony H-804s before (which have varying fretboard radiuses due to chintzy build quality), the outer saddles probably needed filed pretty deep, while the middle two were left fairly close to unfiled, probably just a notch to hold the string in and nothing more.
The Cobain Mustangs - the ones in the store - have a purpose-made 9.5" Radius neck, same as the one found on the Jaguar HH Special actually, which has been available since 1998 and utilizes a similar adjust-o-matic bridge. I owned a Jaguar HH special about 8 years ago, I remember noting how low I could get the action on it without choking out on bends on the upper frets, and how much flatter the fingerboard felt, it was because of the radius difference.
As for the Jaguar, that guitar probably DID have a proper fretboard radius to match the bridge, the neck on it was unoriginal. It originally belonged to Martin Jenner who played with Cliff Richard, and had it's neck replaced in the 80's (reproduction logo, strat-like headstock), and was likely recontoured to follow the Tune-O-Matic bridge that was installed by Jenner or whoever owned the guitar between him and Kurt. I have played a Cobain Jaguar before, the fretboard does have a flatter radius than a regular Jaguar does. If that was not the case, then the Tune-O-Matic on it was much easier to file to the radius because it's an ABR-1, which I've also had on a Jaguar before (my 98' CIJ) - the outer two saddles had to be cut through about halfway to match the 7.16" raidus of the CIJ's 62' reissue neck, and 1/3rd of the way through for the A and B strings.
