The Black Guard don't seem as bad as the Janissaries yet, unlike the Janissaries (who were meant as a proper army from the start) the Black Guard is still a royal guard. This update doesn't describe them as a swaggering force proud and strong enough to dictate terms to everyone else-- they are always playing second fiddle, first to the Banu Angelino and then al-Nasr. Although they cooperate in scheming the scheming is, so far, initiated by other actors that deserve the blame for the fall of the Hizamids a lot more.
I think Europe avoided the troubles posed by Muslim standing armies because they didn't have their own standing armies until much later. During the Middle Ages they relied on a mix of mercenaries, levies, and conscripts that gathered only for specific campaigns. Exceptions to this, like Matthias Corvinus's Black Army, didn't last long (the Army was dissolved by his successor). And even then politics wasn't safe from military intervention. England was gathering some big armies in the Wars of the Roses, sure... after over a century of interstate war and a decade or two of civil war made war in general a lucrative profession, especially for military entrepreneurs like Warwick. If Europe avoided the problems of a single standing army trying to capture the central government and run it themselves, it still ended up with several smaller armies trying to sabotage the central government, with some success in pre-Valois France and rather more in the Holy Roman Empire.
The examples most similar to the Muslim case (wars over the central government) would probably be the Carolingians, who were the Merovingians' "mayors of the palace" until they took the palace for themselves; the Norman conquerors of Southern Italy; the Sforzas, a dynasty of upjumped condottieri who rose and fell by the sword; the Dutch Republic, essentially a confederation of urban militias and merchant fleets; Napoleon taking over Revolutionary France.