No. The Belgian law should be interpreted in the light of European Directive 95/46/EC, and more in particular of its article 26.4. This article provides that Member States have to take the necessary measures to comply with the Commission's decisions regarding standard contractual clauses. Contracts based on the European Commission's standard contractual clauses therefore do not have to be authorized by Royal Decree.
A copy of the contract has to be sent to the Belgian Privacy Commission, however, so that it can examine correspondence with the European Commission's standards. Moreover, these processing operations have to notified in the Privacy Commission's public register, except if the applicable regulations regarding notification stipulate otherwise.