problems with people search (bug?)

As you probably know we can search person by last name using following search query in SharePoint:

LastName:a*.  That's all good and well, right? Wrong.  Search does not work at all.  Results I expect to see when I query with LastName:A* (oder by Lastname) would be something like:  FirstName, Aa; FirstName, Ab FirstName, Ac; ; FirstName, Ad. 

Problematic results I actually see:  First Name, Aa; First Name, Ab ***First Name, Ba**; ; First Name, Ad,First Name, Äb.

So we have three problems. 

Fist problem: Search returns unwanted items. result "First Name, Ba" should not be returned because I query users whose last name start with letter "A". Search actually returns few users whose last name or first name contains character a. 

Second problem:   Search  returns users whose last name start with non English characters like Å, Ä, Ö.  Those characters fill be mapped to english as follows: Å > A, Ä > A, Ö > O.

Third problem: "OrderBy:Lastname" does not work as expected.  

Is there any work arounds / solutions I can try?  For me this seems like bug.