Hi,
Posting to acknowledge this as an ongoing, current issue with the CDP Data Catalog service wherein it lacks support for the 7.1.0 lake versions.
I am unable to find a workaround to it as the 7.0.2 lake version selection has been removed (like you've noticed), which could've been a potential route.
Our internal teams are aware and are working on getting the data catalog service working against 7.1.0 very soon (internal reference for the issue is CDPDSS-365 if you'd like to discuss this over a support case/etc.)
Sorry for the inconvenience!