The AI does seem to be better in EUIV at avoiding unwinnable wars although Burgundy ended up fighting most of Europe in my current game:
They were trying to conquer Lorraine who were initially backed by Bavaria and Austria. Over the next few months Poland, Spain and then Brandenburg (offered Austria an alliance) joined the war. At the end of the war Burgundy only lost 4 provinces.
Spoiler :
They were trying to conquer Lorraine who were initially backed by Bavaria and Austria. Over the next few months Poland, Spain and then Brandenburg (offered Austria an alliance) joined the war. At the end of the war Burgundy only lost 4 provinces.