Is this by design? 

I expected to following

[[file:some-file.org::#some-heading][some text]] 

to translate to this

[some text](some-file.md#some-heading)

So in org-md-link I would have thought that the default would be more like this

(t (if (not desc) (format "<%s>" path)
 (format "[%s](%s%s)" desc path (or (org-element-property :search-option link) ""))))

You would of course have to do some sanity checking on search-option to just take care of id versus headline searches etc.

Regards

Phil