After watching Red Cliff, the Japanese would not think that the uniforms of ordinary soldiers in Red Cliff are the uniforms of the Three Kingdoms period in China, right?

No, the Japanese still appreciate the history and culture of China's Three Kingdoms period. You can see it just by looking at the Three Kingdoms games produced in Japan. I even think the Japanese understand the history of the Three Kingdoms better than the Chinese.

The movie you are talking about is definitely different from the real thing

If you are a Korean, you will definitely say that the Three Kingdoms were caused by Koreans......