Your bibliography template is likely missing the “Link Adjacent Text” command in several places. The Link Adjacent Text command “joins” two or more items together so they act as one unit. In your case, it willlink the comma if: 1) there is a translator; and/or 2) if there is an edition. No comma will be generated if there is no translator or edition.
Suggest you insert the Link Adjacent Text command (noted as an asterick in the example) in the bibliography template as shown below. Note that no spaces occur between the comma and field name.
If you still have problems, add the modified output style and we can tweak it for you. My version is attached, in the book template, so you could open it and paste it into your template.