Installed locally, the widget works good. Don't think it is hosting problem, because I have numerous sites at this host and every site has this widget installed, no problems before.
Anyway, case is solved with Big Brother, thanx for advice. Customer was so excited by this feature - to see Google Analytiscs on the dashboard, that, to my mind, it was the main reason to choose MODX
Coudn't dissapoint them!
Log file warnings can see in my first post, but this is not important anymore, hopefully, I guess.