Sorry to hear about that problem. I do see the problem with the giant quest starting early. I have gone through the entire game and replicated your issue. I found the problem with the seed dialogue bug not showing up and fixed this to not be dependent on the main quest.
To do the giant quest, you will have to finish the story up until the H-scene with Odette. After completing that, the Giant side quest and farming side quests should fall sequentially. Please download V. 0.15c. However, this may require a new save file due to some of the changes.
Thank you for reaching out with this problem!
- Seed