Even as a Pentecostal, and later an evangelical, I disliked the “many mansions” translation. A better translation would be “dwelling places.” The context is that of a Middle-Eastern house, which is an entry into a central courtyard, surrounded on all sides by dwelling spaces, usually on at least two levels. When a young man became betrothed, he would prepare a living space in his own father’s house, and when the space was ready for occupancy, he would go get his bride and consummate the marriage, and they would live in the spaces prepared in his father’s house.
The idea that when we get to heaven, each of us is going to have a 50-room, gold-plated “mansion” smacks of Western hyper-consumerism.