I want to build Editor X integration using REST APIs if possible. Please let me know.
since you want to build integration, our Dev Support would be best people to assist you, they got own channel for assistance with such question, please see it here:
https://devforum.wix.com/account/connect-sso?redirectUrl=https:~2F~2Fdevforum.wix.com~2Fen~2Fcontact