Barbara Walker: Woman's Encyclopedia of Myths and Secrets, "Kingship"

On page 506, in the article on kingship, Walker says:

The Roman word for a king, rex or reg, descended from Sanskrit raj, as did the Celtic rig.[1]

As a source for this particular statement, she provides Dumezil's  Archaic Roman Religion. Which actually says that rex, raj and rig descend from Proto-Indo-European (admittedly, I only obtained the French version):

 il est remarquable que, comme celui de la société védique (raj(an)), comme celui de toutes les sociétés celtiques anciennes (rig-), le chef de la société romaine primitive porte le vieux nom indo-européen *reg-. Ce seul fait assure que les habitants des cabanes des montes tibérins n'étaient pas des groupes de familles inorganiques, qui au bout d'un certain temps, se seraient associées en créant des institutions nouvelles, mais que, au contraire, ils étaient arrivés aves une structure suprafamiliale, politique traditionelle : comment supposer en effet que ces hommes qui, d'un lointain passé, avaient hérité, aves le mot, la notion de rex, l'avaient d'abord laissée péricliter pour la réactiver ensuite, sous le même nom?

Or, si nous ne connaissons pas directement le rex latin, la comparaison du rí irlandais et du rãj(an) védique permet de concevoir avec quelque couleur ce qu'était le *reg- indo-européen, duquel ils sont dérivés.[2] [my bolding, any omitted accents are solely my responsibility.]

Can we trust a source that seems not to understand what her sources say? How many such mistakes does it take until the book's credibility should be  considered entirely debunked?

This is not just for the pleasure of debunking or tearing down someone's credibility - this is a serious question to any fans of Murdock's (or to herself, even) - if an author repeatedly proves themselves incapable of getting right the very things they quote from another author, how credible are their claims?

[1] Barbara Walker, The Woman's Encyclopedia of Myths and Secrets
[2] Dumezil, George: La religion romaine archaique, avec un appendice sur la religion des Etrusques Bibliotheque historique, 1974

Barbara Walker: The Letter 'A'

In 'The Woman's Encyclopedia of Myths and Secrets', the very first article concerns itself with the letter A.

Sacred Alphabets of the ancient world signified birth and beginning by the letter A. This letter meant the Creatress, who invented alphabets and gave them to mankind - though most traditions said womankind had them first.

Babylonians called the Great Mother "A", the Beginning; or Aya, the Mother of All Things.¹ [1, article "A", the entire article has not been copied here]

As source for this she gives "Assyrian and Babylonian Literature, Selected Translations", New York: D. Appleton & Company, 1901. Pages 133-134.

As luck would have it, a searchable version of exactly that book is now available online. Turns out the claim is not explicitly supported by the book she refers to - Aya does not occur once, all the more so not at pages 133 and 134. "A" does occur, but without any further elaboration as to what it refers to. This does not justify claiming that the source supports the claim.

Sources:
Walker, Barbara: The Woman's Enyclopedia of Myths and Secrets

Assyrian and Babylonian Literature, Selected Translations, New York: D. Appleton & Company, 1901