The OK button is Power Pivot dialog box when creating relations is missing in the Swedish version but OK when switching into English version 1902 (11328.20146).
We are following up with the Excel Localisation PM @Roger Clarke to investigate. We will come back when we have news. Thank you so much for letting us know about it!
The Excel Dev team have just applied a fix for this issue in their fileset. While we cannot give you the exact date it will get to customers we hope it will be in next months Office365 subscription update. In the meantime you should be able to use the Enter and Esc button to invoke the "OK" and "Cancel" buttons. We are sorry for the inconvenience this caused you and others.
