Here's my one and only experience with a croquembouche:
The only fiasco was the spun sugar for the croquembrouche which collapsed because it was raining the day of the wedding.
Oh, yes, and the fact that my pastry bag couldn't easily pierce the creampuffs. Testruns had shown a 1/4" opening was perfect! and it wasn't--the puffs cracked! So I was filling them with a mini-plunger and could only fill 3 creampuffs before having to stop and reload it with the pastry cream. Fill, fill, fill, stop, open plunger, refill plunger, wipe off plunger, wipe off hands, fill, fill, fill. STOP. SWEAR. Open plunger, fill....
Finally, it was midnight on Friday and the first 100 puffs were finally done with 230 more looming in the background when suddenly I had an epiphany! Basically, I didn't give a hoot anymore if the cream puffs cracked!
So I grabbed that pastry bag with my burnt, blistered fingers (oh ya, THAT happened everytime I dipped one of these little suckers in the hot scalding caramelized sugar where--by virtue of physics and the "center of mass" theory--they would flip over onto the TOP of the creampuff and immediately adhere to the closest dipped puff, demonstrating conclusively the Nils Bohr postulate of covalence bonding between negative electrons and positive pastry protons.)
Well...Lo and behold...the pastry cream (take 100 egg yolks, 1 gallon of milk, 1/2 gallon of heavy cream, six cups of sugar, slug down a healthy shot of Frangelica liquor....) held the puffs together even when they cracked.