« I am skeptical about the assertion that this is "a letter of the Latin alphabet". Since when did Latin ever have pharyngeals? Or voiced fricatives for that matter? Unless I am very badly misinformed, someone must have added (or proposed adding) this letter at some later point in time for some purpose entirely unrelated to Latin. »
in fairness the reason we have to call it “Latin” is because “Roman” contrasts with “Italic”