First, under normal circumstances, the change of the ownership of the leased house does not affect the performance of the lease contract. Article 229 of the Contract Law stipulates: "If the ownership of the leased property changes during the lease period, the validity of the lease contract will not be affected." In other words, after you rent out the house, it is sold, but it will not affect your lease contract. During the validity of the lease contract, you still have the right to continue renting, but the object of paying the house rent becomes the new landlord. A more explicit legal provision is the second paragraph of Article 1 19 of the Supreme People's Court's Opinions on Several Issues Concerning the Implementation of the General Principles of the Civil Law of People's Republic of China (PRC): "During the lease period, if the property rights of private houses are transferred due to sale, gift or inheritance, the original lease contract will remain valid for the lessee and the new owner."
Second, according to what you said, the intermediary informed the house for rent only after the house lease contract was signed. You can also claim that the lease contract is invalid because the other party deliberately conceals important information about the rented house, and you can ask the other party to compensate you for your losses.
Third,. Article 230 of the Contract Law stipulates: "When the lessor sells the leased house, it shall notify the lessee within a reasonable period before the sale, and the lessee shall have the preemptive right under the same conditions. According to you, the house was not sold when you rented it, so you also want to have the preemptive right under the same conditions.
To sum up, the sale of the house will certainly not affect the rental, and you will certainly enjoy the corresponding rights after renting. However, in order to avoid disputes, it is recommended that the intermediary find a suitable rental house. After all, the house has been sold, and how to deal with the relationship with the new landlord is still unknown.