I would recommend using
LocaleSidKey fields from a context
User. Based on that you can set specific locales on mobile before displaying the data.
From User | SOAP API Developer Guide:
Required. This field is a restricted picklist field. The value of the
field affects formatting and parsing of values, especially numeric
values, in the user interface. It does not affect the API. The field
values are named according to the language, and country if necessary,
using two-letter ISO codes. The set of names is based on the ISO
standard. You can also manually set a user’s locale in the user
interface, and then use that value for inserting or updating other
users via the API.
Required. The user’s language, such as “French” or “Chinese
(Traditional).” Label is Language.
In API version 47.0 and later, when using the DescribeSObjectResult
API to return PicklistEntry values from this picklist, the
value indicates whether the language is in the user’s Displayed
true) or the user’s Available Languages (
false). All other
languages aren’t in the returned
active value array.
In API version 46.0 and earlier, the PicklistEntry
indicate whether the language is in either the user’s Displayed
Languages or Available Languages lists (
true) or not in either list
These fields are not available through
UserAccount class in MobileSDK but having other fields from this class you should be able to retrieve locales by REST/SOAP request.