I'm not sure if you are experiencing an error or if the column types are just not as expected, but I was able to create base views with TIMESTAMP_NTZ and TIMESTAMP_LTZ data types on the same Virtual DataPort update as you ("denodo-v70-update-20190903") using the default Snowflake JDBC driver. I've included my base view's VQL below so that you can see the mappings done by the wrapper:
ntz = 'NTZ' :'java.time.LocalDateTime' (OPT) (sourcetypedecimals='9', sourcetypesize='0', description='', sourcetypeid='93', sourcetypename='TIMESTAMPNTZ') SORTABLE,
ltz = 'LTZ' :'java.time.OffsetDateTime' (OPT) (sourcetypedecimals='9', sourcetypesize='0', description='', sourcetypeid='93', sourcetypename='TIMESTAMPLTZ') NOT SORTABLE
In Virtual DataPort, TIMESTAMP_NTZ becomes TIMESTAMP, and TIMESTAMP_LTZ becomes TIMESTAMPTZ. If you would like to convert those data types to something else, you can always do so.
You can read more about timestamp data types and how to convert them in the [Data Types for Dates, Timestamps and Intervals](https://community.denodo.com/docs/html/browse/7.0/vdp/vql/language_for_defining_and_processing_data_vql/data_types/data_types_for_dates_timestamps_and_intervals) section of the Virtual DataPort VQL Guide.
Hope this helps!