Balts + Sarmatians = Slavs. And Slavs + Sarmatians = Bulgarians (and maybe Serbs and Croats). Makes sense.
Now, seriously, there have been a number of articles that would require a serious correction (I’ve requested it for the ones about Vanga’s predictions and the Volga Bulgars, f.e.), though I was pleasantly surprised that at least in the article about the Macedonian dynasty of Byzantium, they eventually removed Tsar Simeon’s portrait and replaced it with a new one of Basil II.