There’s no solution yet. If you have any additional details that might help us solve this, please let us know. For example, for the friend whose text messages end up in foreign characters, what kind of phone is being used, what carrier are the text messages coming from, and what kind of text messages seem to have it happen? (Long text messages? Text messages with an Emoji? Any particular Emoji, or all of them?)
Please also open a ticket explaining what’s going on, share screen shots in the ticket (not here, because we’ll see personal contact info) and ask that the ticket be investigated as part of master ticket 1508934.
(Pinging @Ambassadors for situational awareness.)