I think they would've seen aircraft lights and stars with their eyes. I wouldn't expect NVG to see through clouds.
https://www.ainonline.com/aviation-news/2013-03-04/nvg-essential-tool-helo-pilotsNVG do have limitations. SRT’s Gadbois explained that pilots need to learn how to avoid flying into IMC while wearing goggles. “If you haven’t been trained properly on what to look for,” he said, “you can get into weather you probably wouldn’t have got into [without NVG].” The problem is that with NVG, it is possible to see through some forms of clouds, so the pilot might not notice that conditions have deteriorated. “If you see wisps, you’re probably in the clouds,” he said. “If you’re new to goggles, you don’t catch that right away.”