Custom translation - not working for eg. email Invitation placeholders


Under Administration > General > Translation, there is a Custom Translations option, where one can put JSON definition, where keys are languages containing a dictionary of key and translations.
I created the following translation:
{ "en": { "Join_Chat": "Come and enjoy" } }
I was expecting that a custom translated text will appear eg. in “Invitation” or “Registration” email text, sent to users. Namely, Join_Chat placeholder is used in “Invitation” text Body.
But default text “Join Chat” appears in received email, instead of new translated text “Come and enjoy”. Like there is no Custom Translation defined.
Can you help me here, what I’m doing wrong, please?

Server Setup Information

  • Version of Rocket.Chat Server: 3.2.2
  • Operating System: Official docker
  • Deployment Method: docker
  • Number of Running Instances: 1
  • DB Replicaset Oplog: Enabled
  • NodeJS Version: v12.16.1
  • MongoDB Version: 4.0.18
  • Proxy: nginx
  • Firewalls involved: Yes