Bad code is not an issue of the development language.
I am around with PowerBuilder since 1994 and have seen a lot of code.
There have been simple architected big applications easy to maintain. And complex architected nightmares. Worsed are those by C++ or Java coders writing PowerBuilder code without understanding the Datawindow.
But I agree, that the PB-IDE (Classic) needs some modern features to support refactoring like you have with Resharper for C# or have in the Eclipse IDE.