Short articles, prevailing on the channel, can be a good choice for 'External feeds' if they’re going to gain their audience’s sympathy with brevity. Also, there are a few medium-length pieces.
Advanced readability level of 'External feeds' content is probably targeted at well-educated subscribers as not all readers might clearly understand their texts. There are also articles with medium readability level, which make more than one third of the channel’s content.
Neutral sentiment normally indicates an unbiased attitude that prevails in the channel’s articles (e.g. it may include some kind of scientific or professional materials).