I have and content type, which has Element as base type. I prepared two resource files to provide localization - AppDB.resx and AppDB.pl-PL.resx for Polish language. I also created custom fields with display names referencing to that resource. Unfortunately, when I deploy my content type feature, every single field is translated properly when I switch languages, but not Title field (where I have set manually DisplayName to point to my resource) - it always stays as it is set in AppDB.resx (invariant one).
I even tried removing title field reference from content type, created custom field called Name, added reference to that field with same DisplayName string and the result is exactly the same. After further looking, it turned out that when I define custom field and set it's display name and add FieldRef to that field without DisplayName change in the FieldRef- it's translated properly. But when I decide to override DisplayName in FieldRef, invariant string is always displayed. This is very confusing to me and this is second day I'm struggling with this. I appreciate any help.
I found workaround, but I'm not very pleased with it. I left content type as is, and I modify display names of problematic fields in list definition schema. But I'm still open for solutions.