nah, even by deng's own requirement China has restored capitalism. He wanted capitalism restrained to foreign investment and for the public/collective sector at 90 percent of the economy, without a development of large domestic capitalism. China post deng liberalized extremely hard which has only been put to a halt by Xi. By literally any Communist definition, even by the one who started 'reform and opening up', China does not have a socialist economy, but a state capitalist or even just capitalist one. The problem is the governing structure is explicitly socialist, and governed by a communist party (although some areas are not very devoted to communism at all, and want to restore capitalism like the Shanghai clique). But still, this is at most state capitalist as the base of all things under marxist analysis is the economy.

Its hard to say they are or aren't building socialism because i see them at a crossroads. They can increase socialist reforms or increase capitalist ones. Socialist restoration is possible but needs some strong movements to get rid of the groups who restored capitalism in the first place.