I am not aware of any plugin translators.
But I suspect, you can try to use "share" for that purpose, to pass the message to a translator program that is capable handling it.
I just checked and Google translate can receive the text that way.
No, unfortunately, you cannot save a message. But you can "share" it to a text editor, and save there.
And just in case you need to save the message: In the same "share" menu there is also "copy" text option.
You can paste it in any text editor. (I like Jota text editor).
I hope this helps.