1)
What are "Gulos ha'Kosaros"?
1.
Metzudas Tziyon: They are the bottom halves of the crowns. Malbim - the crowns consisted of two Gulos, i.e. half-balls.)
2)
What is the meaning of "veha'Gulos ha'Kosaros Al Rosh ha'Amudim Shetayim"?
1.
'Rashi' (Divrei ha'Yamim II, 4:12): There were two Gulos, one on each pillar.
2.
Malbim: There were two Gulos, which comprised one crown, on each pillar.
