I cannot access to my Top 200 sites (error page)
You are referring to data entry? The Top 200 is properly showing on your profile (http://worldheritagesite.org/new/community/Wojciech+Fedoruk). I will deal with the data entry next and address your findings then.
It is a bug. Will investigaet tomorrow when I am back from my business trip. You do not see error messages for a reason: security. It is turned off.
Bug found and fixed (awaiting deployment). There are tags listing the same site (in this case Istanbul) multiple times. I didn't anticipate that.