I checked this in the 1910 census for one of my ancestors and see the same issue. You can click on some fields and get the pop up box to add alternate info, but not for the name.
While I was looking at this I noticed another issue with the 1910 Census index: There are separate columns for surname and given names, but the column headers don't include Given Names, so the headers are over the wrong columns for everything to the right of Surname column.