I wanted to know what were the roadblocks for the retrofit not to work.
That's a perfectly reasonable question to ask. As you probably know, tower computers (Mac Pro, the classic PC desktop etc) are easy to mod, but laptops are harder.
It's still possible to mod laptops, and with mac laptops, people have installed different coloured glowing logos, swapped the optical drive for a second HDD or SSD, retrofitted fingerprint scanners or different wifi cards (that was a while ago) etc.
Retrofitting a lighted keyboard into a MBA is a lot harder. The MBA is insanely small, almost everything in it is custom designed and made, and very tightly fitted together.
It's possible that the illuminated keyboard is slightly thicker, or a different shape, so the other components have been shuffled about to make room for it. Also it requires a special power connector, which your MBA is not likely to have.
Don't let me put you off though. If you have electronics skills, there's nothing to stop you purchasing an illuminated keyboard as a spare part, and disassembling your MBA to try to install it. The iFixit guides are a good help.
Another option is to wait for someone else on the internet to do it, and post a guide to how to do it. Given the level of interest in the MBA, if it's possible, no matter how crazy, someone will do it.
