My observation at this stage is simply this...
All of that seems highly sound to me. The whole system is flawed because it is not based on what is going to happen in play, and especially not what is going to happen in play over and extended period with players that have experience and ultimately mastery of the system.
Your elephant in the room shows that even if they spent a lot of page count developing lists for each monster, the long term payoff of that isn't going to be that great. In a system designed just to inform player choice, players will just read the monster manual and make the choices without recourse to the in game action. Such a system will only have limited utility in situations where the GM creates a custom monster as a puzzle monster, and those sorts of encounters typically are "a little goes a long ways" since as with most puzzles inserted into game play they often don't have a fail forward situation if the players fail critical dice rolls.
Think of the principle here as "Your gameplay still needs to have compelling components even when the player has all the spoilers."
Not saying there can't be an answer to this question. Saying the rulebook gives me the impression its devs think there is such an answer without clearly communicating it to us.
You are making the assumption that the developers have thought through his and developed this system organically in play as one that contributed heavily to their enjoyment of play, and my guess is that neither is true. They've neither thought through this nor developed it as a result of lengthy play testing. They just needed a system that sounded good and went with it.
Let me suggest that you've planed the system and revealed it as empty, and the only fix is getting a new system that has math that works.
If it were me, I'd have "Recall Knowledge" be a martial buffing system, were the player called out facts in a way that aided other members of the party. The exact nature of that fact can be as granular or abstract as you like, but you still have the same concrete result - bonuses to hit, bonuses to AC, reduction of damage resistance, etc. You can still use "Recall Knowledge" to learn specific facts in the systems intended usage if you like, and you need to feed in game information known by the character to the player, but when that well is running dry the action still has usage.
Even then, the elephant in the room remains: why can't the players engineer opportunities to watch and study these monsters from afar and gain the crucial information "for free"? (And once they've beaten their first skeleton or hobgoblin or chuul or whatever, why can't they spend some time making Recall Knowledge actions until they feel satisfied they know everything there is to know in anticipation of meeting another such monster in the future?)
If it is a martial buffing system, all of these problems go away and become opportunities to say "Yes."
"Yes, if you study the monsters from afar for at least X time prior to combat, and have a chance to coordinate plans, with a successful check a party member can begin combat with the Recall Knowledge buff of your choice."
"Yes, if you have encountered and defeated a monster before, then you get a bonus on your recall knowledge check AND you can on the first round of combat get one additional free recall knowledge action."
This also addresses some of your other complaints. How valuable are those feats that enhance your Recall Knowledge action? They might need to be tweaked a little, but potentially, vary.
What happens on a critical failure? Maybe you debuff the intended target by way of distraction or miscommunication or false intelligence?
If you want granularity you could have a system which matched different knowledge types against different monster types for different debuff types. Under that system, comments like, "For example, Arcana might tell you about the magical defenses of a golem, whereas Crafting could tell you about its sturdy resistance to physical attacks" now make sense, as the different skill checks could pertain to different buffs - better spell penetration or better physical damage penetration, or better chances to hit, or more damage from an attack.