As I said, I used the CDD page as a guide, hence the lack of text. I'll add more if it's needed.
The tech is something left behind from before modern I'ee civilisation came to be. The I'ee would, however, have been able to intepret design blueprints and other documentation to produce, maintain and use their own. Most of the I'ee's current tech was discovered in such a way, though some, like the particle drive, is an invention of their own built from another piece of technology they 'inherited'.
The I'ee are like kids when it comes to engineering: You can give them a set of Legos to build a model death star with, but they'll inevitably take it apart and build a haphazard fleet of trains instead. They often learn the hard way not to mess with some designs, and the Alcubierre is one of them.
In short, they inherited the tech, the knowledge to build and use it and how to repair it. As for doing other things, no. The I'ee might have tried adding new 'features', but gave up after the fifth team of scientist waspers got sucked into the tenth dimension. :b