All rouges know thieves cant.
If one rouge in the party is talking to an enemy in a language that an ally rouge in the party does not understand, would the speaking rouge be able to use thieves cant to convey a message to the other rouge who does not know the language being spoken to the enemy?
Would this realistically be possible without raising suspicion from the enemy? How would you as a Dungeon Master handle this situation?
The key thing to note here is that RAW says that thieves cant:
allows you to hide messages in seemingly normal conversation.
So what happens if said conversation is being spoken in a language that only one of the two rouges understands?