It seems that during harvesting, there is no tags validation. This allows you to harvest keywords that are then invalid in CKAN
The only workaround would be to use the clean_tags option, but this is very lossy.
When harvesting from a CKAN instance, it is not as much relevant, but when harvesting from CSW, there can be some keywords that shoudln't be harvested as_is, for instance keywords containing a single quote, parenthesis, etc.
It seems that during harvesting, there is no tags validation. This allows you to harvest keywords that are then invalid in CKAN The only workaround would be to use the clean_tags option, but this is very lossy.
When harvesting from a CKAN instance, it is not as much relevant, but when harvesting from CSW, there can be some keywords that shoudln't be harvested as_is, for instance keywords containing a single quote, parenthesis, etc.