To what extent is the hadith authentic: "None of you should come to his wife at night lest he find something he dislikes, and if he finds something he dislikes, let him call four witnesses..."?

The exact wording you mentioned was not found. However, it is authentically reported that the Prophet, peace and blessings be upon him, prohibited a traveler from suddenly returning to his family after a long absence. This was for two reasons: First, so that the wife could prepare herself by cleaning and beautifying herself, as narrated in the Hadith of Jabir, may Allah be pleased with him: "Wait until we enter at night – meaning in the evening – so that the disheveled woman may comb her hair, and the absent one [her husband] may remove unwanted hair." Second, so that the man would not suspect his wife, for "the Messenger of Allah, peace and blessings be upon him, prohibited a man from suddenly returning to his family at night to spy on them or to seek out their faults." Al-Hafiz Ibn Hajar indicated that this prevents aversion between spouses and encourages discretion. However, Ibn al-Arabi denied that the reason for the prohibition was to prevent the man from finding someone else with his wife, and he weakened the narrations that stated this.