Some files on Plasma Bigscreen’s Gitlab were updated 2-3 days ago, so I think it’s still being maintained.
On the other hand, the Emulationstation website reads:
This website is for the original EmulationStation, last updated in 2015!
Without having tried it, I think ES-DE may be a better choice nowadays, since that one seems to be maintained.
RetroDECK bundles ES-DE with relevant tools and emulators if you want to use it for emulation of games.
impolite7537@sh.itjust.works 4 weeks ago
They have picked Plasma Bigscreen back up but it’s not available for public use currently.