Re: R. imitator breeding/calling seasonal patterns?
I have never seen a clutch of eggs in my Varadero viv and I've only ever found one tadpole in a brom but the frogs have produced 15+ froglets.
It takes 6-9 months for froglets to emerge from the water so you are nowhere near time to see babies yet. And if you've only had the frogs since Sept, the male called for several months and has stopped recently then his cessation couldn't have been going on for more than a few weeks, right? I wouldn't worry just yet.
In my case, I added a large groups of Varadero to my big viv and had babies running around 10 months after I heard the oldest male start calling. I'd wait a while longer without active calling before you worry - and that's really only if you spend enough time around your viv that you are unlikely to miss calling sessions. If you have a job or school outside the home your male might be calling while you are away.