I know this is an old post, but I believe my reply would be useful to anyone else that comes across this post.
I have created a package GitHub - acxz/StringCases.jl: Define, validate, and convert string cases which has more features for handling the conversion between string cases, both predefined and custom.
The name choice may be poor in lieu of the existing registered package, but when I created the package I thought the name was a proper representation of the package. Feel free to take a look at the Example Usage section of the README.md for a concise example.