There appears to be a clear problem / bug with implied annual adjustment for Entertainment and to a lesser extent Spirituality. It is impossible to achieve 100% Entertainment for higher population settlements (>1500) in later years no matter how many entertainment buildings you have and how optimally you place them. I am stuck at 82% entertainment (9 festival poles, 3 grand theaters, 6 libraries, everything fully upgraded, books available, libraries max staffed) for a population of c.1800.
Same problem but to a lesser extent exists with Spirituality. I have 9-10 shrines, upgraded grand temple with 3 relics active, everything is placed optimally. Still impossible to get 100% spirituality.
The problem likely arises from “per annum adjustment” parameter for Entertainment which results in the game mechnistically demanding “entertainment per person” which is impossible to achieve in later years. All other parameters (for example Food) are reasonably balanced and it is possible to achieve 100% Food satisfaction even in later years with very high pop.
The problem is only with Entertainment and Spirituality parameters.
Multiple players face exactly the same problem as reported on that forum and FF sub-reddit.