Is it permissible to work on a freelance platform after falsifying registration information in order to get the account accepted, and then restoring it to its original state?

There is no harm in operating websites as an intermediary between professionals and those seeking services for a percentage, as this falls under permissible brokerage (simsarah) and commission (ja'alah). However, it is not permissible to deceive the website if it stipulates certain professions or specific countries, because that involves forbidden lying and deception, and because mutual consent is a condition for brokerage. In the Hadith: "Deceit and treachery are in the Fire." You must contact the website administrators and inform them of the true situation. If that is not possible, you must leave it, and then you can re-register with your true information.