Originally Posted by
warellis
Imaginary Numbers space is primarily used as a form of storage magecraft, much like Jewel Magecraft. You can use it to store various things, form portals to move about quickly, create super realistic illusions once someone is pulled into it (as in the person can now be subjected to such things) and some other stuff that I'll have to look up to remember.
For example, a guy in Clock Tower 2015 uses his Imaginary Numbers ability to store his beer.
Essentially there was no real reason to have her Sakura use Jewel Magecraft when her own innate abilities could already do that.