I found two bugs (so far) ...
1. I place all three of the level II pumpkin sematary at the same time, so they all started producting around the same time. After about 2 hours, when the production time had passed the halfway mark, i buffed them with sandwitches. One sematary kept on going. The other two times were reset back about an hour and a half (about - judging from the movement of the production bar).
2. I sold on trade 6 pumpkins for 1 very strong light, but 2 appeared in my star menu.
I didn't take screen shots, but I can if you wish.