Kines is the noun and kinesisk is the adjective. Sometimes these are the same in Swedish, as in svensk, and sometimes they’re the same in English, as with Chinese. But just as English has a difference between Swede and Swedish, Swedish has a difference between kines and kinesisk.
It sounds better to use the noun in my opinion, but I guess you could use the adjective as well.
No, "Chinaman" is not considered the demonym in English.
The adjective (Chinese) and the demonym (Chinese) happen to be the same in this case, whereas in Swedish we have two different words, or actually three if you add the female version.
Kines - Chinese (male person)
Kinesiska - Chinese (female person)
Kinesisk(t) - Chinese (adjective)
I have (in the UK)... it was intensely awkward! My Dutch colleague was giving a talk, and his supervisor was saying something about how great an example this project was of international collaboration in science. Something like '...A Dutchman, A Brit, an American and a Chinese...'
It made me squirm inside! Never ever use it.
In this discussion for "De lär mig kinesiska", @devalanteriel says that "kinesiska" is also the name of the language. https://forum.duolingo.com/comment/7354300/De-l%C3%A4r-mig-kinesiska
In Australia it was used of Chinese people on the goldfields... and it just feels super racist, like I associate it with the gross stereotyping that went on then. For that reason in Australia I think it was moved away from. Plus “China” not “Chinese” sounds objectifying in some way, plus “man” only.
OMG... I remember a playground taunt from my childhood nearly 4 decades ago that had the word “Chinaman” in it... that poor one kid in my school D:< (Now yesterday I was in the centre of the city and there was a giant movie billboard in Chinese so [parts of] Australian society have very much shifted.)
I’ve heard “the Chinese” commonly used collectively as well as “Chinese people”. Former is commonly used in Australian media but I don’t feel so comfy using it.