They weren't hard to press, they were not easy enough to press when rushing (plus there wasn't anything else going on on the screen so no need to be overly conservative?), which you kind of want to do because there is a timer.
I was just thinking that several times I was going to collect the scones out of the oven, but got interrupted by the bullet hell, and then I think due to transitions I wasn't able to collect them in time, which I would have been otherwise. So you kind of have to make a choice on how you want the game to flow.
Making them burn easier could work, but it could also feel like double punishment, because you already have the bullet hell, but if they burn easier it means that you could start cascading, and fail all the subsequent customers. Maybe making each subsequent bullet hell harder (faster) could be a solution, in that case you want to make sure you don't fail often, while failing once doesn't mean you fail all other orders?