I think this apostrophe is for a 'soft sign', a letter to be found in East Slavic languages. It means one should pronounce the last 's' in a softer way. PS.: An alternative would be 'Kazusj', with the 'j' pronounced somewhat close to 'y' in 'yet', only shorter. Both apostrophe and 'j' are not perfect for the task, though.
Last edited by kecal at 2/22/2023 9:50:45 AM