If primary language A is set in OJS 3.0.2 then submission in language B that is not set as primary will stop at the second step during the upload process. Actually, button Continue will be greyed.
I think that there are two options left:
- let editor upload regardless which language it is chosen for interface (primary or not)
- display message for the user that it is not possible to do that due to reason that it is possible to do that only in primary language
Note: primary and not primary language are selected to be present in submission and forms. I am not sure is that bug or undocumented feature. However, I think that there should be feature that certain roles can do that in whichever language regardless of the status being primary or not.