Write on mail for problems with the site pls, mail is all over the place(here and there and on the apps etc)
For selecting date and time we are using the integrated control into the browser.
За Firefox there is info here:https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/date
So we are using what is in the browser. meaning any bugs have to be fixed by them(and probably will be eventually).
I plan to add manual one for a while now. But this one has the bonus that with browser updates will get better. While if we add something manually it will stay as it is, so while it may not be perfect now(for IE doesn't work for example), as time goes by should improve with browser updates.