"were showcased at" is correct and usable in written English.
It is commonly used to indicate that something was presented or exhibited in a public or formal setting. Example: The latest technological advancements in the automotive industry were showcased at the annual auto show, drawing in thousands of attendees.
Across town, the 20th-century choreographers were showcased at the 19-century Palais Garnier.
Many were showcased at the World Natural Hair Health and Beauty Show in Atlanta.
Some amusing team names were showcased at the Hong Kong Inter-City tournament, sponsored by J. P. Morgan, which ended on Sunday.
Through countless poems and plays -- he continued to write even after his illness was diagnosed late last year -- he defined the Nuyorican experience, inspiring a new generation of Latino poets, including the streetwise slam poets whose provocative performances were showcased at the Nuyorican Poets Cafe, a Lower East Side institution that he helped to found.
Similarly, the Brooklyn-based design group MakerBot Industries had developed a series of desktop 3-D printers in the hope of popularizing the digital production technologies, which emerged as an important theme in design last year and were showcased at the Istanbul Design Biennial and several museum exhibitions.
Whereas past films were showcased at festivals and events, this is the first project to launch from Story Studio after the consumer release of the Oculus Rift headset.
Hot rods, customs and classics will be showcased at the country music singer's theme park.
His latest work is currently being showcased at the Al Ma'mal Foundation for Contemporary Art in Jerusalem.
This month we showed you the flatpack cardboard helmet being showcased at the Cycle Show.
All of this work could be showcased at a careers afternoon organised by the students themselves.
The gulf in class was showcased at this year's Copa America.
