Just looking a bit further, it appears that they may have dragged the names from Place Names, then manually copied the actual heights from the Leaflet map shown on each page there, which is also CC-BY-4.0.
As per the beaches a while back, they should all be reverted & redacted, or do we try for a waiver?
The OSM license change was in 2012 but the waiver guidance was only issued in 2017 and this import was from 2014. Simon Poole authored the waiver guidance post, and also provided feedback on the import without mentioning the license so I think at the time it was just less clear that OSMF’s view is that CC BY is not directly compatible for contribution.