As I correctly understand this sim can't do reversed count  as a real one?

that is correct. pretty much all of the dekatron's used in computing applications were used only in increment mode. i did assume that some people might want decrement in the future, so i have plans drawn up for a design that supports both increment and decrement.

Neither I :)

I want to use presettable Up/Down counters on dekatrons in my DekatronPC project. I still didn't start any schematic investigations for this task, but remember that somewhere reference schema of reversible counter was noticed.

i am not sure i understand your comment, but to do a dekatron sim that support presettable with up/down support would require you to use either multiple chips, or something like a  small FPGA/CPLD. there is certainly room on the back side of the board for additional logic, but it does make assembly a lot harder...

Who talking about dekatron Simluator? I want to build up/down counter on the real dekatrons :)

But in one thing you was right - reversible require a lot of additional logic both to sim and the real one. 

ahh ok, now i understand your statement!