As far as I know, the only wallet that supports electrum seed phrase is bluewallet.
If you want to import your electrum wallet to Sparrow, you have to import the wallet file. You can't import the seed phrase that has been generated by electrum to Sparrow.
You're right, I just did the test here, to import an electrum wallet into sparrow, only with the keystore file. Another point worth highlighting is that Sparrow does not import electrum keystore derived from a BIP39 seed (imported)
It's true that when extending the seed with a passphrase, we will get a completely different wallet but, technically, it's not a password. A password is used to encrypt the seed or the wallet file while the passphrase is part of the seed itself.
However, it's worth noting that extending the seed with a passphrase is not going to add much security if it's not too complex or if it's stored with the seed in the same place.
You may be right about the term.