The missing 2 Settlers of Willem's is an interesting issue. I guess that a Cease Fire therefore does not make a lot of sense.
As to whether Willem would Open Borders... we'd need him to be Cautious with us and he might not want to Open them since they were cancelled recently due to the war (there is a minimum amount of time that you have to wait after Borders are Closed before you can reopen them). So, I don't really think that he will Open Borders for a while.
Ragnar only needs to be Annoyed with us and will Open Borders, so he would do so at any time, given that it's a been a while since our Borders with him were Closed.
As for promoting our Trebs or not, we'll want to check how many turns it will take for them to heal. That extremely-wounded first Treb in the stack that is highlighted in the attached screenshot almost might as well take a promotion now (since it is so wounded) and I recommend taking Accuracy. Any other Treb that can heal in time can wait before we need to decide.
Willem has the Creative Trait so his western City will quickly expand its Cultural borders and steal back his Clam Resource. We have 8 turns before Utrecht would use its 9-square radius and 9 turns before it could feasibly use its big fat cross, so there is time to delay in capturing that new City (the one called Maastricht).
Nice news in terms of the Great General... do you think that with any sort of Galleon chaining, it will arrive in time to be able to distribute promotions to units? Note that we'd need a turn where units could stand away from other units... probably on a Road just outside of a City.
As for Willem's Worker, I would capture it. If nothing else, it can continue to do what Willem was doing with it--Chopping Forests (although I suggest that you do not finish a Forest Chop until the nearby City comes out of Revolt--since Willem was already Chopping, be sure to check the Worker's Chopping action display to ensure that we aren't already one turn away from Chopping). I do not know if Chops made when a City is in revolt will "count" or not. I suppose that someone could test it out easily enough.
We can always disband a Worker later after it has done some helpful tasks (such as Chopping Forests and/or possibly building Forts and/or possibly building Roads).
In regards to a Cease Fire with Ragnar:
- He's less likely to build additional Cities while at war, and with only a core of 4 Cities, it's not necessarily a bad thing to have him build units. In fact, if he keeps "pouring off steam" by sending units on Galleys at us, then he really won't be accumulating anything and will just be pouring away Settler Hammers on futile Galleys loaded with troops.
- If we don't yet need additional Foreign Trade Routes, then given that he keeps sending units out on Galleys, there is no incentive to take a Cease Fire with him yet.
Isabella now has 8 Cities, yikes.
Note that Joao, like Ragnar, while in war mode, does not appear to have been doing any expanding. So, there is a reasonable incentive to have AIs waste their Hammers on pre-Longbowmen troops in favour of additional Cities.