All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions.
At the moment you waived and registered the house at the Dept. of Lands and Survey to your wife, the house becomes hers and you aren’t permitted to dispose at any amount belongs to the wife without her permission as she is financially independent from you, since Allah, The Exalted Said (What means): ” And it is not lawful for you that ye take from women aught of that which ye have given them;” [Al-Baqarah/229] in addition, the Prophet (PBUH) said (What means): "It is not lawful for a person to take his brother's stick except if he is pleased with such." He (PBUH) said so to show the degree of prohibition on a Muslim to take other Muslims’ belongings unlawfully.” [Related by Ibn Haban].
Therefore, there is no harm if the wife wanted to sell the house to you with her consent yet; this transaction remains reprehensible since it involves the suspicion of circumventing in usury. Besides, every transaction involves the above suspicion is prohibited, in this regard, Ibn Hajar (May Allah have mercy on his soul) said: ” Any sort of selling that have many controversial opinions is reprehensible such as circumventions used to conceal usurious transactions.” [Tohfat Al-Mohtaj vol.4 pp.323].
In conclusion, it is reprehensible to take your gift back whether this was through selling or by any other mean. And Allah knows best.