Tantalum caps will leak some current. Yes, it'll be less than the rated value in practice, but still may not be negligible depending on your use case, if you design something ultra low power.
One figure I specifically have mind, because I ran into it specifically, was a design with a 22µF/16V tantalum cap, voltage range was 0 - 10V. At around 3V+ we noticed a current leakage of about 500 nA. That's not a lot, but keep that in mind if you are looking at sub-µA "sleep" currents. That should give you an idea - in your case, the leakage should be typically <= 1 µA.
One thing I'd note from your description is having a relatively large capacitance after a PTC. I don't know how often your circuit is bound to be powered on, meaning the large capacitor will get charged and draw a relatively large inrush current. That may "trip" the PTC for short amounts of time at each power-on cycle and degrade its series resistance over time, which in turn will degrade efficiency. Of course if the device is meant to be powered on at all times and will rarely see power cycles, then that's not really an issue. Otherwise you could add some means of limiting the inrush current.