Yes, Cleansing Bubbles is on a timer and based on it being silenced. From the patch notes:
"The amount of time between the Bozzetto Songstress being affected by silence effects and using Cleansing Bubbles has been increased from 45s to 60s."
Bippin's strategy works, but you can still do it the silence way just fine. We were getting ~6 minute VD kills with minimal risk, silencing the boss 4 times or so each fight. Each time it erases itself, the bard and the healer fill it full of 4-5 enfeebles, then spam silence until it lands. It's got a Resist Silence trait, so it can sometimes take 2-3 casts even if the conditions are met and you have plenty of MACC. If anything, it's easier to silence this time because SE removed its gradual enfeeble resistance, meaning you can land everything but silence 1/1 no matter how many times it has erased itself.
I was the healer on RDM/SCH and it wasn't very hard to heal even when splitting healing duties with getting silence back up every minute. Just make sure to throw out a quick Slow/Para on the kraken when it pops so hundred fists doesn't wreck someone.