Customisation of `@room` and nicknames handles per room

### Your use case

#### What would you like to do?

Be able to alias `@room` or `@username` to something else, for example, to use a different language for room or a different nickname for a particular person.

#### Why would you like to do it?

I'm in various communities that English are not the main language. Therefore, having a setting that alias `room` to `sala` (one of the examples in Spanish), `stanza` (in Italian), or whichever the language is would help accessibility to people where English is not their first language.
I also use [matrix] and element with family members or close friends, which we don't refer to them with the username they've set up for other communities. For example, my dad wouldn't like to be called `@Joe Doe` by me, he would prefer something like `@dad` (or `@papa`, …). Having a way where a user can provide different aliases based on the room they are would also make it more familiar while allowing users to select how they want to be called on different domains.

#### How would you like to achieve it?

I think the easier would be some kind of room (or space/community) setting that allows the admin to define aliases for the room name, and each user to define how they want to answer in that particular room.
I imagine it would be easier to set up on the client than on the matrix standard, but having it on the protocol would make it scalable to other [matrix] clients, which may be a better solution.

### Have you considered any alternatives?

I don't know what other alternatives are available. I've changed the language on element and inspected the translations strings on the translation platform. They provide a translated “tooltip” when adding `@room` but not a different name to refer to it.
I've not seen this feature on other chatting platforms that I've tried, but I think it would be a very nice feature for [matrix]/element to have.

### Additional context

On a family context some people may get multiple family members with the same name: John Doe (dad), John Doe (son), maybe they call themselves Dad and Junior respectively, but not outside their home. John Doe dad may have a `JDoe` username, whereas his son may have a `JohnDoe` – calling one and another between the family becomes confusing and not helpful. To add more confusion, the daughter's name is Jo and `JoDoe` is her username.
(Certainly, the parents could have chosen a different name for their children… but we can't “fix” that from [matrix], or can we?)