Third languages cannot always be successfully rendered in interlingual #subtitling using current norms.
Case in point:
In #TheFamilyMan (S02E01 00:45) an agent from Mumbai arrives in a Tamil-speaking area. He gives orders to the local agent who translates them to the team (in L3

This L3 utterance is meant to be understood by the audience, but not by the Mumbai agent.
However, the foreign audience cannot discern that there are actually two different languages spoken (L1 and L3), so this dialogue must be perplexing:

-[Mumbai agent to local agent in L1]: Follow my lead.
-[Local agent to team in L3]: The guy is an idiot.
-[Mumbai agent in L1]: What did you tell your men just now?
-[Local agent in L1]: I translated your orders