'Confirm check' window: poor English and sub-optimal button labelling
'Depending on the amount of data the file system check takes longer time' is garbled English. Much better would be:
The check may take a long time, especially if the partition contains a lot of data.
Just what wording should be used depends upon what exactly it is that is to be conveyed - that the duration of the check is proportional to the amount of data? That the check may take a long time?
Also: in the buttons, 'Proceed' would be an improvement upon 'OK'.
gnome-disk-utility 3.28.3 UDisks 2.7.6 (built against 2.7.6)