There are two kinds of pilots on TS: the striving-for-expert and the I-don’t-care. Almost everyone on training who is active on the IFC is the former. The latter, there is almost no way to get back to them. They either have ‘frozen’ inactive accounts that they don’t link, or they might not have one at all. So I perfectly understand your frustration, the same happens with me. So after every tracking thread controlling session, I may give the pilots personal feedback. However, I really hope there is no chance for them to succeed on ES if they keep trolling like that. Still, controllers on training vary a lot in quality. We are the serious, aiming-for-IFATC ones. The others, I have had really bad experiences with them. They don’t know what they are doing. Therefore, while a please follow instructions command may work for us, those bad controllers might end up abusing the command. So yes, there is no way to report them in-game. You really don’t know who is at the tower. At the end of the day, the people aiming for expert will see success, while the trollers and unprofessional controllers will stay in TS. It is what it sounds like: a training server. For pilots to train for expert. It is not supposed to be an ultimate goal. Those who don’t fly properly, even if they meet the G3 requirements, they will soon be back on training because of their unprofessionalism.
Therefore, keep trying, and aim for Expert!