I know this is old, so sorry for the bump, just wanted to comment regards 5.02 compatibility as google brought me here regards RWDESIGN.DLL, and it's hard to find resources about it so I figure I will elaborate for others in this situation.
I've had a few problems getting BCW 5.02 working in retail Windows 10 Pro x64, but it *does* work.
Part of the problem was getting the BDE to work - it hung on install. I reinstalled it to x86 using another tool and mucked with IDAPI32.CFG and disabled VirtualStore (HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\EnableVirtualization) - one of those things worked.
'Failed to load RWDESIGN.DLL' was a relatively simple fix. Just open an elevated (admin) CMD prompt, navigate to %BC5ROOT%\BIN (i.e. C:\BC5\BIN), run BCW.EXE, and try and modify a dialog. After that you should be ok, (you don't need to run as administrator every time).
Codeguard seems to work fine too.
One last comment, MouseWheel by Matt Pietrek really helps make BCW usable:
https://www.microsoft.com/msj/0697/hood0697.aspx (download the Hood0697 exe underneath the heading - don't worry it's just a self-unzipper, plus is on Microsoft's own site, there is a MW.EXE and MouseWheel.DLL file in there).