I am wondering if word translated can be used as adjective in the following example.
I have a translated document.
Translate is a verb. In your example, it is acting as an adjective. For example:
"He translated the book." - verb
"This is the translated edition." - adjective
Participles are used as adjectives, both the present participle and the past participle. Translated is the past participle of translate, so it can be used as adjective too.