Answering my own question since the official French copy arrived today: yeah I was right, he calls him Haruchika during that sex scene.
Something else I've noticed is that Tao originally introduces himself with the first name Tao, so I'm guessing that might actually be his real name and not just as a host.
Also the French version is UNCENSORED-ish (white bars). I'm so fucking happy.
I doubt anyone cares about my commentary, I just wanted to add that there's a page mission on chapter 4, 5 and the extra.
Chapter 4 adds some info about Yamato (he's a model) and shows Sumire-san (the long haired host) fuelling Tao's jealousy of Yamato as well as sowing the seeds of future discord by telling Tao that maybe Chika still enjoys being seen as Jin.
Chapter 5's page has Tao literally admitting that it's his first time, not just with a guy, at least he doesn't specify that, telling Chika that he's nervous though not scared as well as some reassurance from Chika.
The extra is just a really hot spread of them fucking, no dialogue.
So, can someone who knows Japanese tell me what is ACTUALLY Chika's given name? He introduces himself as Haruchika but in chapter 5, Tao calls him Shunkei. I looked it up and 春慶 seems to be an uncommon but valid reading of Haruchika although its much more commonly read as Shunkei. So did the translator mess up there or? This is my favourite manga so I'm losing my mind trying to understand it.
I guess I can also wait for the physical copy I've bought (French since there's no official English version) to arrive so I can confirm my theory...