After starting to use Azure B2C custom Page Layout versions newer than 2.0.0, you will find translations are missing on many controls. Documentation is lacking behind, so it will take some trial and error to figure out some of the translation IDs. In the following pictures, you see missing translations marked with beautiful hand drawn red arrows.
As B2C _should_ already include these translations, the only workaround currently is to manually provide the missing strings in your Custom Policy. The following will work for urn:com:microsoft:aad:b2c:elements:contract:unifiedssp:2.1.4 and urn:com:microsoft:aad:b2c:elements:contract:selfasserted:2.1.4.
So first of all, add LocalizedResourceReference elements in the ContentDefinition elements.
Then the actual strings you will add in the Localization element.
Please note that this is not a comprehensive list of missing translations, so feel free to comment below if you happen to have a full tested list of translations that will work with the new Page Layouts.