If you are creating any new group of sites in Mecano access sheet and then providing access to the user in Waiting tab and facing the issue that the Language is not getting updated (i.e. LANG and XLANG columns remains #N/A) in the sheet then you can follow the below work around,

Place the cursor on that particular cell where you need the language to be updated.

Check the formula of that cell,

The number part in the value highlighted in the above screenshot should be equal to the row no. of the last site ( as marked in red arrow in below screenshot ) which you have grouped under the site tab as marked in red arrow in below screenshot,

If not equal, then you can change the value to that particular row no. after which the Language will be updated.