In the QIIME 2 2018.2 release, Metadata ignores empty trailing columns in the file, avoiding the error reported in this topic. The latest version of Keemei supports the new Metadata file format, and the reported Keemei bug has also been fixed.
Note: if you have Keemei installed already, you’ll automatically be updated to the latest version.
There are a number of other changes to QIIME 2 Metadata in the 2018.2 release. See this forum announcement for details on what changed, as well as the updated Metadata tutorial. 