Classify reasons for `converted` test failures

[wmdietl]

Pull request #146 enables tests in the converted directory.
However, 16 failing tests needed to be skipped.
Go through these skipped tests and determine whether:

1. the converted .jaif file is incorrect and needs adapting or
2. the converted .jaif file is correct and the implementation needs to be fixed.

For case 1, a fix to the jaif file should be easy.
For case 2, produce a minimal test case and file a separate issue.