Yes, our Serious Slider plugin is still under active development and we update it periodically (when we feel it is necessary). There have been no major structural or functional changes in recent WordPress version so we don’t expect any issues in using the plugin with them even if we have not updated the “compatible up to” indicator value (yet).
We prefer to develop and release new updates when constraints demand for an update (to fix discovered bugs or add new functionality), and we like to do this in larger, rarer sets.