The thing about the black hat: if you really understood where she comes from, you’d understand the black hat. It’s not really something subject to much interpretation. She wears a broad brimmed black hat due to cultural requirements.
With regard to the human inhabitants of Tschai, they really aren’t futuristic or contemporary at all - yes, they are familiar with modern technologies because they exist with regard to the alien cultures, but that is all.
With regard to some difficult words - are you referring to words such as: bellicose, perfunctory, punctilio, peremptory, concordance, obstreperous, avarice, adjudicate, and words like that? These are the bread and butter of Vance novels - there are actually a few books written on the subject of Vance’s writing style.
Everyone except the main (good) characters in a Vance novel are knaves, scoundrels, thieves, cutthroats, murderers, swindlers and con-artists. And even a peasant on the steppes might say something like “Perhaps we could arrive at some type of concordance” after he openly tries to rob you and stick a knife through you. Notice how indifferent the caravan driver is to the crimes which occur outside of his caravan? He is entirely self serving - he could care less who robs whom, so long as it does not cause him any inconvenience.
There really should be minimal modernization to Vance’s world. If you want modern worlds, read The Demon Princes.
Traz and Adam fled from the Emblem Men, not the Dirdirmen. There really were no Dirdermen, except for Anacho, who is hanging out with Traz and Adam. However, in the very beginning of the novel. there were Dirdir, an alien race inspecting Reith’s spacecraft.
There are Blue and Green Chasch, as well as Old Chasch. That’s three alien races of similar descent. There are Dirdir, which are another alien race. There are Dirdirmen, of which Anacho is one, but he is now a fugitive. There are Pnume, an alien race native to Tschai, and Phung, an alien race native to Tschai, and they are similar to Pnume. There are Pnumekin, men who are subservient to Pnume as Dirdirmen are subservient to Dirdir. There are also Chaschmen, and they are subservient to Chasch. There are Wankh and Wankhmen, and some Brits take offense at that, as it sounds like wank, which of course is contemporary British slang, and to some extent, American slang as well. I never gave the term a second thought when reading the books, but some have. In a special reprint, Vance felt compelled to rename the Wankh to Wannek after being pestered by a some people.
You should’ve already encountered a Phung, as one tried attacking Anacho. Go back and carefully read the last paragraph on page 52. It should describe the Phung. Read closely what he is wearing. Read the next paragraph on page 53 where Reith examines him in his scanscope. This is a frightful creature. There is a lot of imagery here. And his wardrobe is very iconic and original for an alien species. Bottomline: you cannot tinker too much with Vance’s imagination - it is unique and because of that, it makes for original material. You do not want to change these characters into the cliched science fiction stuff we see today.
Anyway, the Phung then throws pebbles at Anacho! This creature is mischievious. This is classic Vance.
Try dictionary.com for word definitions. It enriches the reading experience for Vance novels.

It’s a possibility that we’ll leave open. You need to get through at least the second book because there are some great scenes in that book.