Yup, that was exactly my point. The way I've always read/run the whole "hiding" conglomeration of rules is that up until the point a creature decides to make the active choice to "hide" (and the demarcation of this point is the roll of a Dexterity (Stealth) check)... every creature knows where every other creature within range is, even if the target can't be noticed by one of the myriad of senses that make up a creature's "perception". A creature's "perception" involves sight, sound, smell, and touch... all of which are used to find other creatures. And it's not enough for a target to get out of one of those senses, they have to get out of all of them for them to be considered "hidden" and thus unnoticed and untargetable (barring random chance).
Thus the second point of Feral Senses to me is redundant to what creatures already do. Creatures already know where any and all other creatures are if they haven't yet made the choice to roll a Dexterity (Stealth) check. Even if the targeted creatures are invisible.
But really... at the end of the day, all that matters to all players is the game mechanic. The "you don't have to roll attacks against invisible creatures with disadvantage". That's the only part of Feral Senses that actually has a tangible meaning. Everything else is the fluffy, ribbon, narrative explanation that the hiding rules use a lot of, in order to let every table have a series of "rules" at hand to explain away whatever hiding rules they were going to use regardless of what was actually down in the book. And I've always contended that is exactly why they wrote the rules for hiding as they did-- because they knew every DM was going to make up their own rules for hiding anyway, so it was a waste of time for them to get too far into the weeds with it. Instead, they added in a whole bunch of narrative description and intention for what hiding and spotting people hiding was supposed to kind of represent, assuming that the DMs would take that intention and use it as their own personal verification for how they were running stealth and hiding.