Hi Zoran, I’m in the same situation as OP, and cannot find the key bit of information, which is how many coins I have right now. You point us to the Statistics page, which shows cumulative coins earned over various time ranges, but does not show total current count. And it’s hard to extrapolate that number from the data which is given.
This number (“current coins”) is only really meaningful in my current situation: I’ve lost my streak, and when I try to repair it I’m told “You don’t have enough coins to repair your streak”. I want to know how many coins I have know, so that I can decide if it will be feasible to earn enough today to reach 5000 and repair my streak.
Clearly the system knows what this number is. Can it indeed be found somewhere? If not, could you display it on the Stastics page? If there’s no good place for this number on that page, then a decent alternative would be to display current coins on the “Repair Streak” pop-up (for users without sufficient coins). You could rewrite the message quoted above, to something like this:
“For 5000 coins you can repair your streak. Right now you have X coins. Catch up today, and keep up the daily practice!” … You can adjust the motivational message as you like 
I imagine that the main goal of streaks, and coins, and the ability to repair streaks with coins, is all to incentivize daily practice. Making the process more transparent would be helpful for users (like myself now) trying to push through slumps and missed goals.