Tracer and Mercy are the first two routes that we added, back when we literally had no idea wtf are we even doing. Since then we learned surprisingly a lot of useful things, so we are planning to completely rework their stories in later updates.
We are also updating money-making and money-spending in game with the upcoming "Altar" upgrade, which will automate the process of earning cash to make it less stressful and way less grindy, so this problem should be fixed in the coming months.
We are not planning to add lounge, at least not yet, but we are making so every subject will have their own class and you won't have to wait to interact with teachers, since they will always be accessible at any day.
Kiriko is definitely going to be added, maybe not in the next few updates, but she's priority right after we finish Sombra and DVa.