Why did Baidu know that when asking questions, it included the word "Guangju" but simplified it to "kitchen"? Is the combination word "Guangju" a traditional Chinese character for "kitchen"?

Light+jade = traditional Chinese characters in the kitchen.

That word is indeed a way of writing the ancient word "kitchen"

Please look at the examples of ancient calligraphy:

From Zhao Mengfu's "Luo Shen Fu"