Most are hybrids. Read the descriptions.
Yes, that Columbian gold *might* be a landrace strain.
Emphasis on *might*. More than likely it's a Columbian Gold plant that was crossed with the Dutch standby, Skunk#1 (which is a cross between Mexican, Columbian, and Afghani, at about a 75% sativa/25% indica). The Skunk#1 provides a stability and a hybrid vigor as well as allows it to be grown indoors more easily with a quicker ripening time. True Columbian Gold typically takes between 16 and 24 weeks of flowering to ripen. The listed time is 10 - almost 13 weeks on that strain.
The underground cannabis seed trade is not known for it's accuracy in describing genetic backgrounds. You have to be very cautious and also be skeptical of everything. I know World of Seeds (the seedbank that allegedly breeds that Columbian Gold) has a bad reputation on some of its landrace strains, especially since they provide feminized "landrace" seeds, while another company called The Real Seed Company is known for traveling to various areas of the world to collect the pure landrace seeds they provide (which is a different lineup every year). Currently, most of their lineup is Himalayan based Charas strains, thought there is a Lebanese hash strain in their current lineup. You never know what they'll collect next year.