I've noticed that the kaddish printed in most editions of the gemara and mishnayos includes ויצמח פורקניה ויקרב משיחיה (vayatzmach purkanei vikareiv meshichei), without annotations such as "nusach sefard".
Is it possible that Nusach Ashkenaz, which omits this phrase in other versions of the kaddish, includes it specifically for the kaddish said at a siyum?