5
Recent Touhou works tend to have a more central and relatively clear themes, especially in the newer CoLA releases, where there's pretty much a new theme per chapter.
At any rate, as far as modern 2hu themes from current times go, we have :
- Immigration for AFiEU, more specifically the changes new stuff may bring : good or bad ?
- Dehumanization in TH 17, which presents the extreme of two bad versions of the modern world : one where humans are just ressources, and for whom living is just nothing but being exploited ; or another one where they blindly submit to a superior authority that takes away their agency from them (AI to a lesser extent here, one of ZUN's biggest worries)
- Touhou 18, prolly 18.5, but mainly CoLA 36, which talks about value in the economic sense (or rather, ZUN's critique of it :) is it appropriate for financial value to translate to real physical goods that are practical for one's livehood, especially if said financial value can be freely controlled by someone else ? Plus how work should be viewed
-CoLA 37 : AI, and transhumanism to a lesser extent
(There's plenty of others, but these are the big ones that I can identify for the more recent works)
It's worth noting that ZUN's writing is more topical, and tend to have referrences to some ongoing current things of concerns to him : some of his work have referrences to popular stufc around the time they came out, for example a Shingeki no Kyojin reference in a DDC Shinmyoumaru spell, clear allusions to the big cough in Detective Satori, allusions and parody of a certain meme country in AFiEU ... heck, even the latest chapter 37 if CoLA (and prolly Hatate's internet-like-thingy is probably an excuse for him to try to give something that's like social media more presence so that he might comment on it eventually.