1. In the Event sidebar widget it shows all events in all languages instead of NL on the NL page and EN on the EN page.
2. On a page with imithemes – Events List/Grid Widget it also shows both languages.
It looks like the widgets are just querying for the latest events regardless the language?
I have assigned this thread to my developer and he will be assisting you soon. Meanwhile it would be great if you can share your website URL and wp-admin credentials here in a private reply for him to check the issue.