Ref: Contact Picker API API Description

Although this API does not define how UI (or browser) will get preset information from user over set of information provided via API, there should be some input/interaction in advance with user, since this API is not one to define an interface like autofill feature for input element.
This API covers information with human language like physical address or name, but in current set of API interfaces, there is no attribute on language and direction information for text provided via this API.
This API should define a way to get language and/or text direction specified by user, and also to provide these via its API interface. Also this spec should also provide guidance on detecting direction when metadata not available, such as first-strong.

See also Declaring language (for metadata) and Base direction values section (for direction and first-strong detection) sections of Internationalization Best Practices for Spec Developers.