The HTML <meta> element indicates that some standard metadata names should be matched in an ASCII case-insensitive manner. It's not clear if this means that all metadata names should be ASCII case-insensitive, or only the standard names. Nevertheless it's better to skip the problem altogether.
For names that need to be case-sensitive in camelCase, they should be entered in HTML as kebab-case. This means that Guise Mummy needs to convert from kebab-case to camelCase when reading metadata from XHTML <meta> elements (especially necessary for ). It also means that Markdown (or any other non-HTML source) needs to convert in the opposite direction when generating an XHTML DOM tree.