"The architects build buildings."
Translation:Architecti aedificia construunt.
Very good question! No, it isn't, but here it is assumed to be, as it is usually given as an alternative (the first one!) in sentences that imply the verb "to build". Condo means basically "to found" as far ass it concerns cities (condere urbem) or "to compose" (carmina, iura). Otherwise it means "to put something away, to hide, to bury something".
I'm afraid there's plenty of examples with architects build... Like this for instance https://www.ft.com/content/cfe85654-5d31-11e9-9dde-7aedca0a081a
Every lesson has got an introduction (HINTS) which gives the main grammatical or lexicon features. Should you not see them on the application for mobile, have a look at Duo on your computer. That's a step by step grammar and you are strongly advised to follow it. Any way aedificium is the nominative and accusative singular form and artificial the plural one. Aedificio is a different singular form (dative and ablative) used for other functions.