After upgrade lot of the OOTB portlets and pages show a mix of languages for the field names.
The user is logged in as a French User, but some of the fields are not translating to French.
This may have been caused on the actual upgrade where something did not process correctly.
The recommendation is to update each attribute/field manually when it is discovered.
There is no way to batch update these.
Steps to force the update:
That will push the updated translations out.
On custom objects you can push the translations from the Object properties itself. However on OOTB objects that is not available.