So player with 300 neighbours and a level 20 wonder can guarantee 300*5=1500kp/day? The Tome of Knowledge only gives a small number per day. And considering they value KP at 45 diamonds, 1500kp/day is over 60,000 diamond equivalent per day. That seems unbalancing. Maybe one kp/ chest for the three enighbour help chests, scaling up sp a total of 15 at 20th level?
No, not KP per YOUR help, but from your neighbor's help. That way, no one can over-farm it. So, if you get visited by, say, 50 neighbors, you get 50 KP. More visits, more KP. But I see the point of the scaling problem, so maybe just leave it at 1, then it will depend on how well your neighbors respond to your visiting them. Or, there could be a cap put on the amount collected, something percentage-based, possibly. Even have the cap increase every so many levels, maybe 10, so you'd really have to invest in leveling the AW to gain more. It would make the Embassy sort of self-fulfilling: you get 50 visits from neighbors, earning 50 KP, which you put into the Embassy to eventually level it.
Now, why do you say KP is valued at 45 diamonds? KP is cheap as far as the devs are concerned, or they wouldn't have made so many different ways to acquire it. I've got 5 Carting Libraries deployed (and 3 in storage), which gives me 5 free KP a day. I have the Snow Owls set, which is another 3 free KP per day (1 from each building). Add in the 9 extra possible from an evolved Moon Bear (if you feed it), and the 5 or 15 packs you can craft in the MA fairly cheaply, and you can already get 25 or more a day in addition to what you earn (which, if you use a KP spell every 2 days doubles your earning rate). Heck, I spent the past month or so parked just outside Chapter 14 and decided to not spend any of the KP I got so I would have enough to whip through the next chapter; I had nearly 1500 KP in the bank. If you're basing that value on the cost in diamonds to buy a KP, that's not a true value. That's Inno's 60+% markup charged to players who are impatient enough to not want to wait until they gain KP the normal way. Right now, 1 KP costs me 277K coins; do you really think that amount of coins is also worth 45 diamonds?