The error you’ve shared is coming from syslog-ng itself; it looks like your plugins are not correctly configured. There are a number of issues which can be found by searching Google for “Error parsing destination, destination plugin”, about a variety of different plugins. Generally, the issue seems to be with how the plugin is installed and configured.
There is also a prototype RFC5424 (syslog) parser for Telegraf that you might be able to use. You can find it on the rfc5424-parser branch of Telegraf. This is still a work-in-progress and hasn’t been merged into master, but it works in conjunction with the “socket_listener” plugin.