That’s not a variant of Ahmad the name, it’s an eccentric variant transliteration of it. Transliterating that particular Arabic sound to "ch" evokes a "k" sound

That’s not a variant of Ahmad the name, it’s an eccentric variant transliteration of it. Transliterating that particular Arabic sound to "ch" evokes a "k" sound, and that’s how ignoramuses pronounce it, "Akmed". There is no such Arabic name. The fact that a few people named Ahmad have been mistransliterated as Achmed in no way means that it’s a legitimate variant transliteration. It is simply wrong, and your Wikipedia link is just documenting instances of a mistake. The "ch" or "kh" diphthong is properly and correctly used only when transliterating the Arabic letter خ. The name Ahmad only contains the letter ح, which has a completely different sound.