If you duplicated the track you “might” be able to run a Nyquist code snippet to isolate the coughs then use Analyze > Sound Finder… to label them. See: https://forum.audacityteam.org/t/need-pointers-on-adding-feature-to-search-pattern/33729/2 and the post below that. I would not be too optimistic if the coughs are mixed in with the audience noise.
Also you may need to run the snippet on subsections of the audio rather than on the entire length at once, because it will take some time to run.
Gale