Feature request: AI diplomacy and religion (this is a long post)

Before creating

[X] This is NOT a gameplay feature from Civ VI, BNW, or outside - see Roadmap
[X] This is NOT a gameplay feature from Vanilla Civ V or from G&K - If so, it should be a comment in https://github.com/yairm210/Unciv/issues/4697

Problem Description

It is frustrating when the AI nations see a powerful player-controlled civilization (more powerful than them) and just do nothing. They do nothing to address the problem and just sit idly (or boost their army size at best), as if waiting for the superpower to just devour them. Or when the AI does not care to make alliances or coalitions. Here I try to give some ideas for the further development of diplomacy and religion in Unciv, which could make the political experience even richer.

Desired Solution

I propose the addition of the following AI behaviors and features:

When an AI nation feels threatened by a roughly equal player or non-player civilization (e.g. not in a defensive pact or friendship at least), it should try to ally with another country or just invade alone by surprise in order to force a desirable peace.
When an AI nation borders or nears one (or more) overwhelmingly powerful (relative to itself) civilizations, it should always try to strike a defensive pact or friendship with at least one of them. Then, the weak nation should try to play its powerful neighbors against one another and to gain a better position in relation to them (for example, take some cities or at least destroy some of their units, helped by its ally). And the AI civilization should look for allies in other regions, as well. Essentially, in these situations it should strive for a balance of power which it might exploit and overturn when it becomes stronger.
When a superpower (no matter player or AI-controlled) looks poised to conquer the whole world, the remaining AI nations (even old enemies) should forge defensive pacts (or a coalition, described in point 5) in order to discourage the superpower from attacking.
When a large and powerful nation suddenly starts to look weak (due to rebellions, lack of finances, exhaustion from a war etc.), its neighbors (may even be weak or mid-tier, but feel an opportunity) or other great powers should try to invade and defeat the civilization to score a decisive victory and get a favourable peace treaty. Negative gold especially should be a great motivator for them to do so, but it should come with a big diminishing of strength on the large nation's part if a war is to be waged.
Nations should be more willing to form alliances and coalitions to achieve common interests. I propose the following motives for them to do so: common enemies (esp. if more powerful than them), trade and science benefits (when in a pact, nations should get some financial or scientific bonuses, but not as large as with research agreements), common religion (if they want to protect their religion from encroachment by larger and more popular ones or just to spread their faith by way of conquest). Especially from the Industrial era onwards coalitions should be more common. A coalition is a defensive pact that any nation can join and automatically becomes an ally of all its members. Coalitions should be accessible from a Join coalition button when trading. A coalition might be joined only if the most powerful civlization in it (called the Coalition leader) or, otherwise, at least 3/4 of the nations approve. Each coalition could be assigned a name (player-made ones may get a name from the player/s).
The following strategic reasons for a declaration of war could be introduced: large gold deficits on the part of either the aggressor or defender; the construction of citadels on the border between the two nations by the defender; large unhappiness in the attacking civilization (the aggressor wants to get luxury resources to boost happiness); a need for gold; the refusal to meet an ultimatum (described in point 7); the refusal to meet a demand; religious fanaticism (described in point 8) and so on.
An ultimatum is a trade which a civilization tries to impose on another nation. The receiver should get three options with regards to the ultimatum (agree, disagree or declare war). If they disagree with the ultimatum, the sender might declare war or opt for peace. Ultimatums should give a stronger pressure than a normal trade, but if the receiver agrees they should get a short-term happiness penalty for acting cowardly. Conversely, if the receiver does not agree, but the sender opts for peace, they should get the same penalty. If the receiver decides to outright declare war, no one gets a happiness penalty. AI nations should give ultimatums not only in a position of power, but also when in great despair or when sensing an opportunity to overturn the regional balance in their favor.
A religion should have a Fervour scale with three divisions: Cosmopolitan (1-10 Fervour), Intolerant (11-20 Fervour) and Fanatical (21-30 Fervour). Fervour could be increased or decreased by certain beliefs. Cosmopolitan religions or pantheons emphasize harmonious existence with other nations and faiths. A civ with such a religion cannot attack another state of the same religion. It can declare war on a country with another religion, but then it gets a mid-term happiness penalty, expressed with the formula: P = 11 - F, where P is the penalty and F is the Fervour. This formula should work only for Cosmopolitan religions, else civs would get unfair happiness boosts. Intolerant faiths are sceptical of foreign influences, but they are primarily defensive in nature. Nations with such a religion should get a long-term happiness penalty when a foreign religion becomes dominant in one or more of their cities after the Intolerant faith has been adopted and the city was originally tied to this faith: P = (C * F)/11. Here C is the number of cities that have turned to another religion. Nations with an Intolerant faith could get a bonus when fighting in their own cities which profess this religion. Fanatical religions are those that despise everything foreign and preach the destruction of all foreign beliefs. They are also the most nationalistic. The happiness penalty mechanic related to Intolerant religions should also apply here, but now any city that professes another faith (no matter if it was its original religion before the Fanatical religion was even founded) brings happiness down. And, on top of that, the penalty is doubled. Finally, a Fanatical nation might get a slight but mid-term happiness penalty for allying with a civ where another religion is dominant. The state religion should be considered the one dominant in the capital. If there are two or more religions on par in the capital or no pantheon/religion exists in this nation, then these mechanics should not be applied. But Fanatical nations could get a bonus when fighting in all of their own cities and in enemy cities. A religion or pantheon should always start as Intolerant, of 15 Fervour, by definition. Inquisitors should be available only to Intolerant or Fanatical civs.

Alternative Approaches

I have not considered alternative solutions to enrich the gaming experience, but I will appreciate it if my propositions attract the attention of the developers.

Additional Context

No response

yairm210 / Unciv