Liquorice swirls add to the difficulty of making colour bombs.
It takes a lot of moves to remove the 4-layer icing, and when the player manages to destroy the icing, chocolate spawners will start producing chocolates, which may be a problem if the chocolate is ignored.
The rows of icing and swirls limits the playing field at the beginning.
2 color bombs, that's not a problem at all. You can do this in two ways. One, you can get rid of the 4-layer icing and have more room to make a color bomb, however one of the dreaded chocolate spawners will start spewing chocolate somewhere. Another way is to leave the 4-layer icing, but you'll have less room to make your Color Bombs. It's still possible that you can make your color bombs and complete it without breaking one of the 4-layer icing.