Exactly what it says, someone died during your building process. You didn't had the required potions..
I'm hoping you have a savefile prior the building process so you can take your time to get the potions.
Probably affect interactions with you and Logan/Ste when it's about the Country Road I guess... Everyone survived at mine so I don't how it all goes if you failed.
I don't know how far you are, currently the most recently added story portion was for Orc's War where you had to look for Groth, met Kalghor and Nameless at Plains if Death.