I was sure BIP39 isn't supported by the coldcard. I'll double check and reconfirm. I think it was in the docs if you have to restore wallet from compromise or loss/damage with seed directly, this wasn't the option to pursue.

I guess best option is to test (like suggested) with dust through an air gap signed send with the electrum xpub from the coldcard. I suppose I'm just overly skeptical it will work not seeing the lack of correlation with the xpubs from dump file.

Update soonish.