No, browser doesn't want to send file content with this mime type.
If you use the browser to send requests, it may be better to convert your data to CSV via XQuery:
csv:parse($input, map { "header": false(), "separator": "semicolon" })
How does your html look like, which you use for sending the request via the browser?
"header=false,encoding=CP1251,separator=semicolon"
RFC describes "text/csv" mime type. Are you sure that "text/comma-separated-values" is the correct one?
True, text/csv should work as well!