In Russian перипетии (peripetii) also means unforeseen and negative circumstances
That's interesting. :) In Greek, περιπέτεια could have both negative and positive meaning. In fact, there is a particular phrase, "περιπέτεια υγείας" (directly translates to health adventure :P), that has a negative meaning, probably of some health problem that someone was struggling with for a while.
That's actually very poetic, makes it seem like something that begins and ends with many twists and turns along the way.
Greek περιπέτεια is the source of Spanish peripecia "unforeseen incident", "suddenly change".