Unexpected PROJCRS.BASEGEOGCRS.CS node in WKT2 strings

csv/pe_list_projcs.csv contains WKT2 strings like the following
```
PROJCRS["Madrid_1870_Madrid_Spain",BASEGEOGCRS["GCS_Madrid_1870_Madrid",DATUM["D_Madrid_1870",ELLIPSOID["Struve_1860",6378298.3,294.73,LENGTHUNIT["Meter",1.0]]],PRIMEM["Madrid",-3.687938888888889,ANGLEUNIT["Degree",0.0174532925199433]],CS[ellipsoidal,2],AXIS["Latitude (lat)",north,ORDER[1]],AXIS["Longitude (lon)",east,ORDER[2]],ANGLEUNIT["Degree",0.0174532925199433]],CONVERSION["Lambert_Conformal_Conic",METHOD["Lambert_Conformal_Conic"],PARAMETER["False_Easting",600000.0,LENGTHUNIT["Meter",1.0]],PARAMETER["False_Northing",600000.0,LENGTHUNIT["Meter",1.0]],PARAMETER["Central_Meridian",0.0,ANGLEUNIT["Degree",0.0174532925199433]],PARAMETER["Standard_Parallel_1",40.0,ANGLEUNIT["Degree",0.0174532925199433]],PARAMETER["Scale_Factor",0.9988085293,SCALEUNIT["Unity",1.0]],PARAMETER["Latitude_Of_Origin",40.0,ANGLEUNIT["Degree",0.0174532925199433]]],CS[Cartesian,2],AXIS["Easting (X)",east,ORDER[1]],AXIS["Northing (Y)",north,ORDER[2]],LENGTHUNIT["Meter",1.0]]
```

The CS[] node in the BASEGEOGCRS[] is illegal according to the ```` grammar at http://docs.opengeospatial.org/is/18-010r7/18-010r7.html#73