I think the mystery around it is exactly what they're going for. They're nearing the end of their successful careers, they don't need to advertise or "get famous".
plus in modern days that everyone (almost) uses the net all you have to do is click upon google
''Songs Of A Lost World'' to find out what is it all about
I said it before i 'll say it once more
Robert Smith is a genius
And yes,this is their last (studio) record as an existing band.
In the future of course they will be released some stuff but the band won't be active anymore.
Enjoy the waiting as much as you can
or maybe again that is just me
Except Google, at least where I am, returns (also) the lyrics of "Lost" when you search for "songs of a lost world"... 🤷♂️