lack of translations for metadata field names in API responses

[mw0000]

Why are some Dublin Core field names translated in API responses while others are not, even though they have their translations in .po files?

{
    "id": 55,
    "url": "XXX",
    "order": 16,
    "name": "Miejsce urodzenia",
    "description": "",
    "comment": "",
    "element_set": {
        "id": 3,
        "url": "XXX",
        "resource": "element_sets"
    },
    "extended_resources": []
}

{
    "id": 37,
    "url": "XXX",
    "order": 100,
    "name": "Contributor",
    "description": "An entity responsible for making contributions to the resource",
    "comment": "",
    "element_set": {
        "id": 1,
        "url": "XXX",
        "resource": "element_sets"
    },
    "extended_resources": []
}

Element 37 has been translated:

Omeka/application/languages/pl.po

Line 94 in cd661c3

#. Dublin Core: Contributor element name

[zerocrates]

The one you're listing first isn't Dublin Core metadata: note that it says it's in item set number 3.

"Miejsce urodzenia" isn't being translated there, it's Item Type metadata that was created with that label. The elements API doesn't translate those names at all.