I recognized another bug which seems to be major: I was breeding cattles and one of the events triggered (the natives claim for cattles short after you have started breeding). I gave them all cattles in order to achieve +2 relationship with the natives. The next round I joined the city screen and recognized this: Cattles have now a negative value of approx. -1.300 and every building (!!!) demands for this amount cattles. The effect is that no building incide the city will be finished now (I delivered tools in the city but nothing happened, the building was not finished).