Looking at the pcfg, the tag descriptions are not kept in the CVT section of the file. Additionally, when the tags are created in "CVT runtime.lvclass:create index groupings.vi", it looks like only the data type and name are used to initialize the tag. This also explains why the default values are not correctly passed to the CVT.
After figuring this out, then digging a little, it looks like the default value issue was fixed for the latest version of the module available on github. Here's a link to that issue: https://github.com/LabVIEW-DCAF/CVTModule/issues/26. If you wanted the CVT to include the description, you could possibly do it in this vi. The description is not in the dictionary, so you'd have to look up each tag and get its description. Alternatively, you could add the description to the configuration editor for the CVT module and then pass it through the configuration at runtime.