What exactly is the problem with "Default Joomla router" when JoomSEF is enabled? "Doesn't work" isn't much descriptive. Make sure you have "Parse Joomla SEO links" enabled in JoomSEF's Advanced configuration.

Hi.

This is the component in problem.

extensions.joomla.org/extensions/calenda...OiJ0YWJsZSBlZGl0Ijt9

This component is about creating tables with data in joomla. When Joomsef is enabled I cannot edit any cells in table even if I choose "Default Joomla Router" or even "Component's Router".
This was working fine with previous joomsef. Now I had to choose "Not Using SEF" in order to be able to edit my tables.
The component if free. You can try it.

Regarding Greek language problem, you are right. It is a K2 bug with the Greek Language.

We'll check the component and let you know.