I cannot vouch for the accuracy of this site (or any others really) which seems to define the Brazilian differences:
But if so then the differences in BR and EU PT are numerous.
A "varanda" in Portugal is attached to the home and can be any level including ground level but not part of the ground (though there can be a gate and stairs (if needed) to the ground/yard:
Varandas do not have to be covered but are enclosed by some sort of fencing.
What in Brazil is called a "sacada" is more like the varandas in Portugal – though I have not yet seen any that big or luxurious which are more like what would be called a terraço in Portugal and which does not have to be the top floor, as it states in the article linked above (notice the varandas above the terraço shown below).
This is in keeping with the English meaning of "terrace":
And in some cases what might also be called, "deck" in some areas in English (and also "esplanada" in Portugal at least when part of a business).
Portugal is the land of the Varanda!
A house in Portugal with many varandas and a terraço at the bottom (though the one in front at the top might also get called a terraço):
Language is so complicated! =}
The best way to learn a language is to mesh it with your own. If you do not know how the "new" grammar fits in with the "old" grammar, it is extremely difficult to guess correctly with new sentences. Use this as a learning experience to help you learn more about preposition grammar.
"Camarote" (cabin) seems to be more fitting for "box seats" which are more luxury than just "balcony seats" (which can go up many levels even and get quite cheap). However, I have seen one theater map that shows "camarote" as general seating around and above the floor seating.
Other than, "varanda do teatro" what comes up for me most often for theater/re (or seats) with "balcony" is "balção" but that by itself is "counter" which is quite different.
Maybe it is a European Portuguese thing (though the first image is Brazilian):
So it is interesting this translation is so hard to find online.
In any case, "varanda" for general balcony seems to dominate in Portugal, and in English for a theater balcony we wait, "in" rather than "on" (as we would for an outside balcony).