Good questions, unfortunately it is very difficult to get solid answers as the past simply wasn't documented. The first texts on Karate were published in Japan (Funakoshi in Japan 1922,1925, Mutsu 1933, Mabuni 1934/1934 and so on). They described the training of their day, but only oral history has any real links (that I've seen).
To give you an idea how difficult this is, let's look at your question on Unsu.
The Pai Lum system (Daniel Pai's White Dragon) system has a form which is a very close clone of Unsu. Pai was from Hawaii, and his system seems to be a bridge of various Chinese systems. [I don't study Pai Lum, and am going on Oral history from trusted sources.] Their Unsu similar form (I belive called Prance of the Panther) could be used for speculation as a Chinese source of Okinawan kata.
But Karate was demonsrated in the past on Hawaii (including the Okinawan population there) from visits of various Okinawan Karatela. It is not impossible to imagine someone watched the form during several demonstrations, and simply memorized the movements and then incorporated the form into the Pai Lum system.
Now I'm not saying that is the case, but it is a possibility.
With 28 years young into my own training, I find it far more important to know what you can do with what you have, as opposed to finding older versions. I guarantee you can do everything you need without doing that.
The rest is work.
Bushi No Te Isshinryu