Add a broadcast function for translations.

[SIsilicon]

The proposal is simple; create a broadcast function that instead accepts a translation key as an argument, as well as a list of text to substitute within the translation.
This could be implemented using the tellraw command. And could also be extended to errors in custom commands when one is thrown.

[jrcarl624]

The custom commands error already uses this for errors...

            if (!getCommand) {
                data.cancel = true;
                return this.runCommand(
                    `tellraw "${data.sender.nameTag}" {"rawtext":[{"text":"§c"},{"translate":"commands.generic.unknown", "with": ["§f${command}§c"]}]}`

^^^^ found in /src/libraries/Minecraft.js