Based on a blog entry (http://blog.feedly.com/2015/07/31/10-ways-to-optimize-your-feed-for-feedly) we added the webfeeds:cover and webfeeds:icon on our test environment but when loading in our feed it still shows me the default cover and icon. Is there anything I missed or is this future not available anymore? (even though the blog post it quite recent).
We are working on a wordpress plugin that will help you customize your feed. It is still in beta but let me know if you want to try it.