I'm not certain but I think needs to be merged into
Billbergia 'Fantasia' which is the legitimate cultivar name. "Marbled Rainbow Plant" is a common name.
The Bromeliad Society International Cultivar Registry has a listing for the cultivar 'Fantasia' but no cultivar by the name of 'Marbled Rainbow' and I found it at the following sites listed as 'Fantasia Group', Marbled Rainbow Plant .... which leads me to believe it is indeed a common name, rather than a legitimate cultivar:
http://www.uky.edu/hort/sites/...
https://www.lifestyle.com.au/p...
http://www.plantthis.com.au/pl...
