You just hit the issue related to sensory spells extended to more than one target.
I invite you to read Sensory spells & group
More specifically, David Chart comment.
And further clarification between single target (but not the mage) and multiple targets, especially if you don't understand why granting new sensory ability to one target is so different that granting it to a group (answer, during playtest, it was overruled even if it was logical and consistent with the main rule).
In a nutshell, once a spell targeting a sensory attributes, the only way to grant it to more than one person with a single spell, it becomes a MuMe with requisit and basic level based on the initial Intellego spell, plus an added magnitude. So usually, the group spell version will have to deal with one or two requisits (+1/+2 magnitudes), plus additional RTD modifiers.