Siri: call someone using local contact name spelled in non-Latin (local contact and Matrix ID are linked via email)

So, I have the following setup:

- iOS 10.2 using the Russian language for both UI and Siri
- a contact of a certain person in iOS address book, with their name spelled in Russian and with their e-mail address provided
- the same person uses Latin spelling of their name in Matrix but has their e-mail address linked with their ID

Here, I _can_ find the person via their Russian name on the "People" tab in Riot-iOS (so this proves the binding is actually correct and Riot can see it), and tapping on that localized name shows me the direct chat with them (so this proves the direct chat exists and is also bound to the contact in question).

However, when I ask Siri to call the person via Riot (spelling both the request and their name in Russian), it says Riot can't find the person in question.

Reproduce the Siri call request on iOS 10.2 with Russian UI and Siri, a localized contact name, and an email linked to the Matrix ID. Trace the Riot contact lookup used by Siri and verify that the Russian contact resolves to the existing direct chat; done means Siri can call that person through Riot.

Written by the indexing model from the issue text.