This works for me:
en:
hello: "Hello world"
bye: |
Bye!
See you!
error: >
Something happend.
Try later.
Usage:
irb(main):001:0> I18n.t 'bye'
=> "Bye!\nSee you!\n"
irb(main):002:0> I18n.t 'error'
=> "Something happend. Try later.\n"