API to get list of all available Ranks in community?

Thanks for the idea lilim, upvoted!

Meanwhile I wrote a dirty export script, just execute it within the inspector console on the ranks page in Admin, it will inject a download link called "Export Ranks" which when clicked will give you a text file to download (just rename the .properties file to .csv or .txt or whatever you need, doesn't really matter, its just text):

jQuery('<div id="ranks" />').hide().appendTo('body'); // create fake container for .load() 
// The ranks are embedded with an iFrame in Admin, and
// therefore not accessible directly via JS, that means we first have to fetch
// the content of the iFrame, inject it into the DOM and then work from there...
jQuery('#ranks').load(jQuery('.lia-component-admin-widget-user-rankings').prop('src') + ' .admin_cell:last', function() {

	var ranks = []; // initialize variable
	
	jQuery('#ranks a[href*="edit&ranking.id"]').each(function() {
		var $item = jQuery(this);
		
		var title = $item.parents('td:first').next().text().trim();
		var id = $item.prop('href').split('=').pop();
		
		var output = `rank.${id}.title = ${title}`;
		
		ranks.push(output);
		//console.log(output);
	});
	
	//console.log(ranks.join("\n"));
	
	var file = null;
	var buffer = new Blob([ranks.join("\n")], {type: 'text/plain'});
	var $link = jQuery('<a href="#" download="ranks.properties">Export Ranks</a>').insertBefore('.lia-component-admin-widget-user-rankings');

	// If we are replacing a previously generated file we need to
	// manually revoke the object URL to avoid memory leaks.
	if (file !== null) {
		window.URL.revokeObjectURL(file);
	}
	file = window.URL.createObjectURL(buffer);
	
	$link.attr('href', file);
});

of course you would need to tailor the output to your needs, I needed it for rank translation, therefore it is generating the proper text keys to overwrite rank names...