Anyone who deals with real world repetitive tailwinds, will attest to the fact that a standard flare WILL result in a float. After a while you get a feel for it. The only way I can describe it is that the aircraft is quite reluctant to settle down. After a lot of trial and error it becomes predictable and you will know just how little of a flare you need for a perfect tailwind landing.
Why?
One of my theories is that the indicated airspeed (IAS) increases on a tailwind landing. Think about it. In a headwind landing you will often loose a few knots during the last 30 feet of the approach due to the decreasing wind. The same happens during a tailwind, however as usual, a reduction in tailwind will lead to an increase in IAS. And it is this increase which will lead to a floating tendency. This is just my theory, nothing else.
Other avenues to explore are the higher ground speed and its effect on ground effect..