Probably unrelated, but… what have you done to the engine to loose key parts of it? O_o
Also you don’t have to un-install/re-install you can re-verify engine files from the Epic launcher. It essentially does the same thing and re-acquires/downloads whatever is missing.
As far as swarm goes after you launch the build it pops up as a process accessible through your taskbar hidden icons, and it probably would have told you what was being processed/if it was working or waiting on something.