She becomes good if you take the feat +2 HPs per level at level 4.
I think you would be better advised to increase her DEX to 10 and her CON to 14 at level 4. This improves saving throws as well as AC and HP.
She can "borrow" Lae'zel's half plate to improve her AC. At level 1 she can cast Shield of Faith on herself. At level 3 she can cast Mirror Image on herself which is stronger than the PnP version.
One issue is that there are a lot of good spears in Chapter 1, but Shadowheart is ill advised to use them since (unlike PnP) they require two hands, and she can't afford to do without her shield.
Her ability scores seem to be 1 point lower than they should be - 26 rather than 27