If it were me, I'd probably also be trying with -zapwallettx and -rescan to abandon the unconfirmed tx.
That does recover the coins from the unbroadcast tx. But that doesn't change the reason for the tx being rejected (segwit tx on a non-segwit chain) so any coins currently owned by a Datacoin address beginning with 'd' (as opposed to 'D') are effectively now unspendable.
Cheers
Graham