"How many dining rooms do you have?"
Translation:Quot triclinia habetis?
Cenaculum and triclinium both appear in the course, so I presume both should be accepted here. A triclinium is a couch running round three sides of a table for reclining on at meals, and by extension a dining room. Cenaculum has cena as its root and is usually an upper storey room for dining in. Caenaculum is an alternative spelling that the course creators may or may not deem acceptable.
Note caenaculos would be wrong anyway. It should be caenacula as it is second declension neuter and you want the accusative plural here.
It seems a rare word, few dictionaries include it.
Caenaculum seems to be rather "an attic", but is also defined as "an upstairs dining room", according to the Oxford dictionary.
I have no idea why a dinning room would be set upstairs. Maybe a latinist could explain?
It seems to be also related to the "cena" (last supper) of Jesus. I didn't find a definition, but I suspect it could also mean the room where Jesus had his last supper.
Another book gives the definition "Dinning room, holly style". It seems to confirm that.
The -ne particle turns things into yes-no questions. You don't use it with other question words. It would be a bit like saying "How many do you have dining rooms?" One question at a time. "Habesne triclinia?" Do you have dining rooms? "Quot triclinia habes?" How many dining rooms do you have?
The -ne particle is not required as quot already makes this a question. In any case -ne should be attached to the first word of the sentence, not necessarily the verb. So, "Do you have dining rooms?" could be either habesne triclinia? or tricliniane habes? The difference is one of emphasis, "Do you have dining rooms?" and "Do you have dining rooms?"