Have emailed Florian's to ask about reserving inside, but response is confused/confusing. Is it possible to reserve inside? And in mid-April, is it necessary to reserve?

I have walked past Florians a few times in April, and noticed that there were mostly a few vacant tables. If you were to swing past a couple of hours before you wanted to eat, I am sure that they would hold a table for you if you ask.

Rather fun to take coffee in a place that was trading 50 years before Thomas Jefferson was cranking up his political career ...

Florian's is not the type of place that requires a reservation. I suppose some tourists might think "getting in" is stressful, but on normal days it isn't. Even on very busy days, the turnover is very quick since most people are there to sip a simple coffee, tea, or hot chocolate. Easter week might be busy, and a lot depends on the weather and time of day you visit. If the chairs are set up outside, there are plenty of places to sit. Apart from Easter, April is not considered a busy month for Venice.

I don't think it's necessary, it's a cafe! We went on Christmas for lunch a couple years ago and found it to be a regular ol' cafe vibe.

I can close this thread, with thanks for your responses. And you were right. I finally got a definitive response from Florian's to my email inquiry, and they said they don't take reservations. I'm sure those who said there's no problem in April are right.

No, I don't think it's necessary. I have been to Venice 3 days ago and I have visited Florian Cafe, and without reservation we found a table in 2-3 minutes, and we are talking for Carnevale Season!