It would be nice if you could edit stereo or 5.1 sounds as if they were mono. I use Audacity for editing dubs so everything I do effects all channels (cut, normalization, fade), nothing is for one channel only. Stereo shows up as one audio, so it’s easy to edit, but 5.1 sounds are inconvinient to edit in Audacity.
A feature that is planned for the future (but don’t hold your breath, it could be a long way off as there are very few developers, and lots to do), is to support multi-channel tracks. Currently we have mono (1 channel) or stereo (2 channel) tracks, but in the future Audacity could support 3, 4, 5, 6 … channel tracks.
One feature that Audacity has now that may make editing multi-channel audio more convenient, is “Sync-Lock”. You can read about it here: https://manual.audacityteam.org/man/sync_locked_track_groups.html
There’s also a keyboard shortcut: Ctrl+Shift+K
This extends a selection vertically to all tracks.