I've started to look into Jakandor. I do see some Indigenous American motifs (e.g. 'ghost shirt' spell), though it looks to be pretty blended and removed from direct sources. I'll aim to sift through it. A general "indigenous/tribal/barbarian" vibe doesn't "count" for the chart. But you're right, there are some motifs to be gleaned.
At a quick glance, the other culture on the island has a fair number of Egyptian motifs.