Can I use an administrative (official) appraisal from an expert to sell my real estate property?

Certainly not. The expert has calculated the administrative appraisal as a comparative value against the purchase price for the tax revenue authority in order to declare the real estate acquisition tax. The calculation is strictly based on the law and the Decree on Valuation of Assets. This appraisal has nothing to do with the market appraisal of your property for sale.