But is Tim really immature? Mostly he comes across as very competent and confidant, and somewhat cold, to be honest. As for Jason, he is becoming steadily less angry and violent. They seem to be quietly pushing both DITF and UTRH into the background and letting the influence of those stories gradually fade away. They have already done something of the kind with Barbara and TKJ, and as the new direction unfolds that story will probably be effectively retconned.
It will be interesting to see what the resurrected Damian's personality is like. As with victim Barbara and angry Jason, assassin Damian can get very old and turn into a dead end.