Hi Tatami,
the list of supported functions for the Kunena plugin are available here:

www.selfget.com/documentation/jbackend-joomla30/kunena-module-api.html

Not tested yet with the latest Kunena 5, but it should work.

At the moment a plugin for RSComment or RS TIcket is not included in the subscription yet. It is possible to ask a quote for a custom implementation, but in this case I need the list of the functions you really need to implement (i.e. it is not possible to just say, I would like to have all Kunena functions). A simple list like the following (as example) could be enough to get a rough quote:

1) Create a category
2) Edit a category
3) Delete a category
4) Add a post to a category
...

Moreover, you can develop custom extension by yourself following this guidelines:

www.selfget.com/documentation/jbackend-joomla30/developers-guide.html

Kind regards
Luigi