Hi sukhontika. Since you are an editor, it's better to ask these questions in the internal editor forum.
But yes, you can certainly apply to be an editor of more categories, however you should read the feedback you got carefully - as an editor, it is your responsibility to add sites with titles and descriptions that conform to the guidelines. Part of that is using the right language; titles and descriptions must be in English in the English-language part of the directory, but in the Thai part, it must be in Thai. The people who send in sites for review do not decide what the title and description should be in the directory, and if they provide English descriptions, you need to rewrite them in Thai. That way, the directory does become much more useful.
Again, please ask these questions in the internal forums, or don't hesitate to get in touch with me or some other senior editor if you have questions.