Can Twitter feeds from Feedly be used outside of Feedly?
The short answer is no.
Twitter sources in Feedly do not rely on the RSS/Atom/JSONFeed protocol, they rely on a custom integration we built using Twitter's APIs. This means these RSS URLs for Twitter in the OPML file will not work with any other software.
Twitter sources are also private.
An OPML file with Twitter sources can only be re-imported fully into the same Feedly account. You can tweak the URLs to re-import it into another user account (e.g. migration) with some simple text substitution, but it would still only work on Feedly.