Allows the caster's vision to compare what it sees with what the caster would feel if he touched the images. This has two main effects. The first is that visual illusions that don't overlap with physical objects or that can't otherwise be touched are transparent, seeming hollow like smoke. A fake wall or person is easily identified as such provided the Imaginem effect didn't cover the touch sense, but a Per+Awa check may be needed to spot details such as a person's illusory hat. Cosmetic illusions that closely match the target it covers are typically not detected, however. The second is that invisible characters and objects which are otherwise tangible will appear as a sort of outline, allowing the character to discern their rough shapes. In combat, this is enough to make an invisible enemy obvious (see HoH:S 33). This spell leaves no outline for creatures and targets that are both invisible and intangible.
This would need to penetrate, since if the spell if unable to register a sense of magical touch then it isn't possible to compare with the visual input.
That was the goal. But light is definitely Ignem. And magi should be able to see illusions that don't Penetrate.
The mess is the result of trying to produce something coherent and medieval that gets those effects. I think it's actually really close, but I don't think it quite works. I suspect that the target set of effects is not logically coherent.
What about InVi, Target vision - a spell which outline magic (spells or persons). maybe with a CrIm effect to let it shine for everyone - aka Farie Fire?