Different “levels” of denomination:

1/ Considered as the most readily understandable:

 [§ 1] Purple and pink twilight reef(s)
 [§ 2] Twilight coralline reef(s)
 [§ 3] Twilight/dimly lit coralline landscape/seascape (the best from a management point of view)
However, this is more than a unique term and this will may be the opportunity of more or less interesting discussions …

2/ We keep coralligenous or better,

 [§ 4 ] We keep coralligenous or better the French term coralligene and we give to it a as simple as possible definition. However, doing so, ambiguities are still there.

First draft for the definition:

 [§ 5] (Twilight zone reefs mainly bio-constructed on hard substratum by calcifying coralline algae widespread throughout the Mediterranean including patchwork of habitats complicated by the action of bio-eroders. These complex biogenic formations provide a number of different conditions of light, food and shelter. They are often considered as biodiversity hotspots gathering numerous sessile and sedentary species such as sponges, bryozoans, corals and gorgonians depending on the region and on the depth, to which hundreds of sciaphilic^? species are associated. These complex environments are a reservoir of natural resources (fisheries, red coral) and form highly valued landscapes sought by divers.
This term “CORALLINE SEASCAPE**” was adopted by the CIGESMED community in 2015 to designate some of the landscapes/seascapes commonly called “coralligenous”, because this term was often used to describe several very different Mediterranean circalittoral^? habitats.)
** here, the final chosen term