A blog post with a title of "Mikro für Konferenzraum" gets displayed just like this, without decoding the ü to "ΓΌ". This happens in both list view and subject line in the message view.
Created attachment 1372 [details] screenshot
This was fixed many moons ago by new RSSyl version, pushed a few days later than this report, which decodes entities in title. See src/plugins/rssyl/rssyl_add_item.c in: http://git.claws-mail.org/?p=claws.git;a=commitdiff;h=7b80f1f639341f9711d9b28b45de2939f1b55728