Plant is small and your light settings are probably fine for now. As it develops a couple more nodes you can increase intensity.
Don’t get too caught up on average temp. Ideally you want your lights on temp to be around 80f or couple degrees higher. That is where you’ll start getting best leaf surface temps. Then dial in your relative Humidity to meet vpd chart for stage of growth you’re in. A drop in temp at lights out is expected, but try to keep no more than 10-15 degrees f lower. Too much lower will enter region where you can start to see plant shock. That is why it’s better to be more decisive with your temps. When you say average is 70, that’s not terrible. But definitely not good if lights on temp is 90f and lights out temp is 50f.