I am bemused by your tech choices. You researched CoL despite not wanting to buiild its wonder, its courthouses and lacking the spare population to run a caste economy. You need construction and could have had several turns producing elephants and cats. You need forges to boost your bottom of the league production from metal casting. Researching MC and lightbulbing Machinery is making the best of the current situation - forges, crossbows and workshops
I also see this as a significant issue in this game. There doesn't seem to be a cohesive plan to tech choices in relation to an overall strategy. Writing was researched early to enable madrassas, but none were built for many turns. Then there's been an alternation of military techs and economic techs without having a idea how to use them. HBR-> Currency-> CoL-> Construction and now back to an economic tech CS.
If you weren't going to attack now the military techs could have been deferred. If you're going to attack military techs should go before economic techs.
Other things I did based on your advice included shifting most of my cities to working as many food-rich tiles as possible, and breaking up my Worker pairs. The latter takes some getting used to, as I still prefer to have them work in pairs; when I move on onto another tile, I sometimes lose track of him and have to spend time figuring out where his erstwhile partner is supposed to go. But it does, indeed, save a Worker turn here and there, so it seems like a better way to manage the Workers even if it requires more micro-managment.
The point of not grouping workers in pairs is to avoid losing worker turns when moving into forests, jungles and hills and also to avoid losing a worker turn when completing odd-turn improvements. It doesn't help anything to ungroup the workers but to continue using them in pairs.
Normally I'm delighted to get one of the very rare and elusive Great Engineers, but I'm not sure what to do with this guy. The only unbuilt wonder I have access to right now is Chichen Itza--ugh. I guess it would tie in well with the Protective trait, but I still think it sucks as wonders go. I suppose I could build it in Najran to assist its culture, but still--it seems like a real waste of a GE to me.
As you can see the GE will lightbulb Metal Casting--which would take me all of 9 turns to research, so that seems far from optimal either. I could settle him, I suppose... but I'm thinking the best use for him would be to research MC on my own and then use him to lightbulb Machinery. Thoughts?
Using the GE to bulb Machinery is probably the best option, but you also can hold onto it until you research a tech that enables a wonder that you want. Using a GS to bulb Philosophy would let it build Angkor Wat, which could be useful if you intend to run lots of madrassa priests at some point. Although the lack of religions on the continent may make a priest heavy strategy less attractive in this game. GL might also be available.
With my whipping done, I switched to my newly-available civic:
Why Caste System now? You're not running more than 2 scientists in any city and aren't likely to for a while (other than in Mecca which really should be working max cottages instead). You should have either stayed in Slavery or switched to Tribalism to avoid the slave revolt random event and save 1 or 2 gpt in civic upkeep.
I rather like the idea of researching CS while building up EPs on Zara then sending my spies to steal MC.
I'm not sure about stealing MC. It looks like you have less than half the EPs you'll need, and even with all 16 EPs/turn directed against Zara you're probably 25-30 turns away from having enough.
Finally, you can cancel the pig<->fish trade with Zara now that Kufah's fish is hooked up. You really should be looking to avoid trading gold to Zara as it helps his happiness and also will be giving him extra hammers if he's building Shwedagon Paya.