The Peasant's War is in no way intended to apply only to Catholics and it is not a bug that you were hit by it. It is an exceptionally nasty event that is always ready and willing to hit any monarchy regardless of religion before 1600, should that monarchy's manpower base fail it and be depleted to dangerous levels.
It is the event that teaches the player that living on the edge (via either loans, overextension, war exhaustion, or legitimacy) can be really nasty in conjunction with pissing away manpower in a government system based on control of the masses in a monarchial system..
Why are you assuming that this should be catholic only? Some of the translations refer to the religious buildings in the text as monasteries, but is that really enough for you to go "since it uses a religion-specific name for religious buildings, it is surely a bug that it happens to other religions?" Is any of the translations so egregiously bad it states that event is catholic?

If the latter, please specific which, so a minor text correction can be implemented.
It was stated repeatedly on the 3rd page of this thread that it made references to the papal states, reading back to the event itself it has some mentioning of PAP_states, having no experience with the coding language apart from tweaking the occasional peasant revolt chance in CK2, I can only imagine that is what they're alluding to.
As far as the events readable text ingame, can't recall the specifics, just know the level of genericness made me facepalm, your entire stability get's decimated right at the moment where a peasant revolt would screw you the most and the game can't even be arsed to tell you anything but that the peasants are pissy? Nothing about what you did wrong, or how you could have avoided it, I vaguely recall something about the peasants wanting reforms? Which as I understand it is complete bull.
Now, I know the term fun doesn't mean much on this subforum, but does an entire empire exploding because of a couple of peasants make any sense history wise? Did peasants all keep in contact with their telepathic peasant senses? If I have godamn Spartacus leading my nation into ruin you better give me a better description then "The peasants don't like you too much" to spend the next 2 hours of my life fixing that randomly generated mess, and an event that triggers when you actually manage to overcome it to help you with the 2 hours you wasted
doing nothing.
Funniest part is the reason my manpower got decimated wasn't even the Mamluks, their army was a joke, and after playing CK2, you become really paranoid about attrition, it was the retarded AI vassals attaching their stacks onto my 15k peasant clearing stack in the middle of Greece that was there during the war to fill it's rather obvious purpose, having had to dance the whack-a-peasant before, causing a constant trickle of attrition deaths.
Halfway down the war when I saw my manpower had plumited, I figured I'd split up the rebel clearing stack as it was 30k with vassals anyway, and send the stack that had the vassals to the front, the moment I took that stack and sent them to the Mamluks, the AI showed it's stupidity again and moved their vassal stack to my stationary stack.
If this is intended, it either forces the player to see vassals during wartime as a danger instead of a... Well, vassal, or leave your country open to get screwed over by any peasant, or if you're unlucky, nationalist revolt.
And it's nothing to do with the translation by the way, I play the english version.
Edit: Looks like Heatth already cleared up the part about the event and it's relation to catholics.