This package is just a fork of language-gfm extended to support some features of markdown-preview-enhanced.
language-gfm-enhanced
in package manager and install it.language-gfm
$...$
and $$...$$
are currently supported. (copied from language-latex)If you found an issue, then check language-gfm first because it might be an upstream issue.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.