Complex sentence: Other problems with using a hotspot to explain this volcanism is the highly variable composition of volcanism between various edifices, and that a number of Cook Islands are not located on the reconstructed path of the Macdonald hotspot.
Split into simpler sentences: Other problems with using a hotspot to explain this volcanism is the highly variable composition of volcanism between various edifices. Finally, a number of the Cook Islands are not located on the reconstructed path of the Macdonald hotspot.