Since you specified in your request, I am assuming you are looking for a review of the specific subtitle files circulating on the internet (often found on sites like OpenSubtitles, Subscene, or ripped from the official Blu-rays) that are marked as "Foreign Parts Only" or "Forced."
Source: Scollo, D. (2018). The Subtitling of Multilingualism in Game of Thrones: A Case Study of English, Spanish, and French Subtitles. Multilingua , 37(2), 151-172. game of thrones subtitles for non english parts verified