What an appalling piece of cultural apporopriation. First there is no evidence at all that the tarot has any historical or mythical link with Africa. Many people claim the originated in Ptolomaic Egypt, but we should be aware that the later Egyprian civilisations of the pre — christian era were Hellenic cultures and the rulers were descendents of Alexander the Great. Though there is evidence that the tarot deck was created in Italy or France in the sixteenth century, the symbolism also has links with Germanic folk traditions. Others say the cards originated in the middle east but were merely a diversion and not though to have any magical powers. Nobody knows for certain, but all the evidence points away from Africa.
There is no evidence whatsoever that Pamela Colman Smith was mixed race, though there is plenty of evidence she was lesbian, (the writer of the article missed a chance to score some politically correct brownie points there.)
Opinions on her ancestry are varied, some claim she was the daughter of American parents who moved to Britain, others claim her father was an businessman from New York and her mother the sister of a successful American artist. There is no suggestion in the few public domain sources available on the artist, or academic sites I have access to that either was black or mixed race though the family did move to Jamaica for a while several years after Pamela was born.
People interested in the folk magic or sub Saharan Africa should research Muti although if you are of a liberal or snowflake tendency I warn you this stuff is not for the faint hearted. As a point of interest, since governments begant to encourage mass migration from Africa there has been a steady increase in Muti related murders linked to migrant communities in British cities.