Love that the old hag was always as mean and bitchy as she is today, but perfect at putting on an act.
The caravan was poisoned, but not really. I'd lean more towards this just being everyday shady statecraft of the era.
- Carvan is loaded with "new" fashion designs where the waist is tighter than previous years, Maomao caught this one for Gyokuyou
- A wide variety of the items available are in combination, more likely to result in miscarriages
- Full-sized mirrors are extremely valuable and the empire would be stupid to turn them down. They're largely using polished copper for mirrors. The empire is currently not capable of replicating them like the Southern European countries
- Gaoshun's mystery to Maomao was clearly a faked story to get her deduction on current matters (much like Rakan would have been used). They toyed with the idea that it was Gaoshun asking about himself or a relative, but he's not that type of person from what we've seen. Two "daughters" close in age and look alike and enjoy Western countries' hobbies like embroidery. He easily accepted Maomao's absurd explanation that a full-sized mirror was likely used while she demonstrated with a round copper one
- The two envoys are cousins that look alike (and we've seen them in the opening, they're more like twins). They were shown many beautiful women the empire had to offer, but quickly scoffed and wanted to see the Moon Fairy, who is likely the very top of what the empire has to offer as beauties.
- Maomao pointed out the painting is likely considered to be embellished it came from, though the old hag knows it is relatively accurate.
- It is common knowledge that the Emperor likes well-endowed women.
- The envoys have big boobs.
Put all this stuff together:
Gaoshun was probing Maomao to see if there was a means for the envoys to separate and do spycraft/assassination, or perhaps more significantly, sneaking off to seduce the Emperor.
The country they're from is trying to figure out how many of the Emperor's consorts are pregnant, because they probably have poorly placed spies getting info from outside the Inner palace. The caravan was used to first verify if this was true, and potentially secondly softball in some miscarriages.
The envoys, either directed to or as a matter of their own pride, are trying to figure out if they actually have competition within the country, since their high-trade country results in high-ranked people becoming very beautiful over generations.
The shady statecraft they're after is very likely the same shit that Lishu and Loulan's families are after, installing them as consorts by political force to have a chance at becoming the Empress, or at the very least have tremendous influence within the palace.
It's also important to remember why Maomao's surrogate and biological father both warn her to not jump to conclusions that the things she sees are connected. They might all be one conspiracy like before, they might all be totally unrelated, or they might be two parallel and completely independent schemes going on that know nothing of the other. Maomao is more cautious now to avoid making those leaps when the evidence doesn't support a link yet.
Given the murder plot with the super-toxic fungus and the speculated motivation behind it, there's also a possibility the miscarriage compounds were an unrelated plot all internal to the palace. This is why Maomao is remembering her father's advice and keeping that hypothesis close.