It seems that the aether is no longer compatible with Traveler's Titles, nor with the visual titles ressource pack.
They apparently changed the dimension name to paradise_lost or something but adding a corresponding entry to a lang file doesn't seem to work.
How do I fix it?
#Traveler's title and Aether
pallid nebula
restive shale
looks like they changed the Aether mod ID from the_aether to just aether. You can get the visual titles resource pack working again by editing the assets/travelerstitles/lang/en_us.json file and changing this line:
"travelerstitles.the_aether.the_aether": "\u2C22",
to this:
"travelerstitles.aether.the_aether": "\u2C22",