Research on explicitation has been criticized by a lack of diachronic analyses and multi-lingual comparisons. This study, therefore, conducts a 50-year (1970–2019) comparison of referential explicitness between a 11,721,608-token corpus of English translated diplomatic discourse from 56 languages and a 11,113,036-token corpus of English original diplomatic discourse extracted from the United Nations General Debate Corpus (UNGDC) with the Multi-dimensional Analysis (MDA) framework. The findings suggest 1) a general tendency towards less explicitation for the English translated discourse in the UNGDC with time, 2) referential explicitation in Arabic, Chinese, Portuguese, and 31 other languages (more often from Sino-Tibetan, Mongolic-Khitan, and 6 other language families) and implicitation in Japanese and 21 other languages (more often from Japonic and 4 other language families), and 3) changes in referential explicitness in the discourses of China, Russia, Spain, and UAE in comparison with Britain and the United States. The potential influence of language contact and source language interference may be further taken into account. With the findings, this study calls for more dynamic views and multi-lingual comparisons on explicitation in diverse genres to present a fuller picture of the translation universal.