Amazed to see these linked to on here! I actually happen to be the same seller of these LED's and had registered earlier this month looking for info on the
Ibiza FR!
They can be got separately from the mounting bar in any number (the bar is made to size for the civic) and looking at the Leon looks like they would be a perfect fit into the vents.
If someone could measure the gap between the vents it'd be interesting to know if they would fit...
One taken from about 15meters away to show the brightness (for comparison the car has 25-SMD-LED sidelights which are way brighter than standard 501 bulbs)