Floating Man-Made Islands Revisited Again

I first pondered the idea of creating floating countries here back in 2012 and in 2014 returned to it using the idea of lopping the tops off Mountains to use in their creation but the owner of the Ben Nevis Cafe at the top of the UK's highest mountain need not worry because a Danish firm have taken my idea and ran with it and no mountain was defaced in its making.  
As the world population grows and sea levels continue to rise due to climate change, our only options are to use the space above our head, the ground beneath our feet or spread out into the sea and as the building of massive space stations are beyond us and living underground has the obvious problems of lack of sunlight and ventilation, the only option left is to build in the sea.     
The Earth consists of 71% of the wet stuff just sloshing about and being home to fish and dolphins but a Dutch architect has the same vision as me and had began constructing a floating City 75 hectares big which could host 10,000 people.
A prototype is already bobbing off the coast of South Korea and has blocks of residential buildings, each with waterfront views obviously and comes with food, water, and energy systems and can sustain itself 100% through solar, wind and wave energy.
Obviously living in the sea comes with problems of storms and stability but it is designed to be anchored to the sea bed to stop movement which can be detached in case of storms and moved to calmer waters.
The United Nations are obviously intrigued as they have appointed their UN-Habitat Agency to take a look and see if it is something they would like to get involved with and help upscale but as the sea level is rising on average by 3.6 millimeters per year and 900 million people living in low-lying coastal areas are in acute danger, they had better not take too long looking at it.