Currently, featured feed content is scraped from individual wikis using custom, per-wiki selectors due to differences in how they lay out and present featured content. This approach is inherently brittle, since it can break at any time due to layout changes; and it limits the number of wikis for which we can practically support featured content feeds.
A better approach is to publish a markup specification containing agreed-upon selectors that the wikifeeds service can use to efficiently identify featured content. This will improve the stability of the service and allow any wiki to opt in to featured feed support if there is editor motivation to do so.
A draft feed content markup specification is published at https://www.mediawiki.org/wiki/User:CFloyd_(WMF)/Feed_Markup_Documentation. We should begin implementing feed content aggregation logic based on it, making adjustments as needed as the spec is finalized.