I think it'd perceive them just fine. The effect is detecting the "Iconic species" emitted by the entity, not the entity itself.
If the effect were designed to detect something about the entity itself (such as if it were designed to detect beings with the Gift at Target Sight), then it would need to penetrate.
I know, I assumed so too. But then I worked on Hermetic Projects and there's a device effect in there that uses the Vision Target, so I had to gen up on that point.
As I say, I don't think a degree of per-saga hand-waving will do any harm, but it does make for an interesting trade-off/limitation.
In my copy of the 5th edition rules, p122 is sample spells regarding Intellego Aquam and Muto Aquam spells. I am somewhat puzzled.
I am guessing everyone else knows the rules which is being referred to so well they they can answer without checking the precise wording, but I have misremembered what the rules actually say often enough that I try to check each time just to be sure. Can someone give me a better page reference? Thanks