~17 turns for Optics from now. If you've got a Trireme pre-positioned around that island city to the south, for a bit of gold you could immediately upgrade it to a caravel to make contact with the civ to your south the turn after you get Optics. Then that caravel could head west while another one could head east from Coanda. After that you may need to self-tech Alphabet (depending on whether you still can't find an AI to trade it to you), may need to self-tech Calendar, then the Coanda and Fippy Great Scientists double-bulb Astronomy for instant completion somewhere around turn 140-ish. I'd wait on even thinking about what you do after Astronomy at least until Optics and Alphabet is giving you a bit better idea of the overall state of the game.
Keep in mind that since you are a Spiritual leader, you don't necessarily need to stay in Caste System all the time if you don't want to. There's a 5-turn cooldown between civic swaps, but you can for example spend 5 turns in Caste then 5 turns in slavery. During the 5 turns in Caste, some of your cities (those who don't need whip production) can starve a bit running excess specialists, while other cities grow up in size. Then during the 5 turns in slavery the cities that were slowly starving rebuild their food storage, while the cities that were growing can whip that population for production. You could use this to get things like the granaries in Gumbolt and Jnebbe built a bit faster. It's not something you have to do, but if you want to get every bit of mileage out of Spiritual it's an option to keep in mind. Things you'd probably like to whip: Gumbolt granary (1-pop whip after the forest chop finishes in 2 turns), Jnebbe granary (any time in the next 3 turns is equally good, after that would start costing you food), Lymond lighthouse (preferably the turn after it hits size-6, where if Thebes has taken the gold tile over it should be just under 30H on the Lighthouse and you could overflow almost 30 hammers into something like Colossus), possibly a Fippy Tririme for eventual upgrade to Caravel with optics or work boat for the new city. If you did it all right, you might be able to for example run slavery from turn 117-122, back to Caste System on turn 122, get some good production without dramatically slowing your teching.
Don't worry about Zara Yaqob expanding too much. He's vastly far behind in tech already and simply falling further behind; when you feel like it you'll be able to conquer him easily, any land he develops in the meantime is to your benefit.
Looking through your cities...
Gumbolt would ideally whip that granary about 7 or 8 turns from now, if you can find time to work a handful of turns in slavery into your civics. A Representation scientist there is more useful than an unimproved plains forest.
Ideally you'd have let Coanda grow to size-5 before starting that settler.
Let Lymond finish that galley next turn if you can; that way it can move E-NE, then next turn when Coanda finishes the settler galley moves N, scoops up the settler, and heads towards the new city. I might consider trying for a 2-pop whip on that lighthouse in two or three turns to overflow hammers into Colossus with an eye to failgold. That sets you up for building the city on turn 127, and a turn 130 border pop from an Artist specialist, so you want one work boat there by turn 130 and another by turn 133 or so. Because the galley will be passing by Fippy on turn 122, if you have a worker in the area ready it can hop onto the galley turn 122, hop off onto the horses on turn 123, pasture them turns 124-128, hop back onto the galley turn 129, and be ready to move again in Fippy turn 130 (or get carried south by the galley to chop forests for the new city).
Thebes is finally going to hit happy cap next turn (for now, at least); that's a sign for it to consider taking the gold back from Lymond since the lack of food surplus no longer hurts it and the Academy can make better use of the commerce. Then it could work the inland lake 2F2C tile, and pass the pigs off to Krikav to grow on. Not sure about the point behind that random workshop between Krikav and Thebes. You don't really want to finish Hanging Gardens in Thebes if you can avoid it; ideally you'd prefer to collect the failgold off it instead. When it's got one turn remaining I'd swap onto something else and starting Hanging Gardens in a second city (such as Krikav). Worst-case you might end up finishing Hanging Gardens eventually, which is not the end of the world.
Krikav looks fine. I'd have stopped with 1 farm - the capital is going to be happy cap pretty soon, which frees up the pigs, so it should have a lot of surplus food soon anyways.
Sampsa and Noble Zarkon look fine. Get a mine on that grass hill for Noble Zarkon to grow onto. Ideally that granary might have been whipped a while ago, but slow-building it will be okay.
If you're thinking about a brief stint in slavery soon, I'd hop off the horses and run 4 scientist specialists in Fippy for the next couple turns. If you want to keep it simple, current mix is fine.
The new city will be useful but not huge, because you don't have Currency for 2 trade routes per city. So most of your cities already have foreign trade routes (2C) that will not be replaced by the new city's overseas internal trade route (2C). Jnebbe will get +1 commerce, and the new city itself will be 2C from trade and 3C from ordinary production, +6C net. Won't quite offset added upkeep costs, probably about 10 gold per turn, so it's actually going to slow down your tech rate slightly in the very short term. Still worth setting up though, about 10 turns after you've settled it, it can be size-3 with probably fish, clams, and a specialist, by which point it is a net positive and it just grows from there. If you weren't going to have Optics fairly soon anyways, you might prefer to settle that city 2S1E - a pretty useless location in its own right, but with one border pop it would make contact with that civ to the south.