17 years on and nothing has changed.
I had an occasion to use my old Webstyle 4 yesterday but got a "There is a problem with TemplOp.dll Please re-install the correct version" error. I tried uninstalling and reinstalling without success. I tried to run it in compatibility (Windows XP (Service Pack 2) mode but no luck.

The advice from 24 August 2005 is Regsvr32 "C:\Program Files\Xara\Webstyle 4\dlls\templop.dll" but I get The module "C\Program" failed to load. Entering just Regsvr32 I get a "To register a module you must provide a binary name error.

My templop.dll can be found in C:\Program Files(x86)\Xara\Webstyle 4\dlls and was last modified 14/10/2003.
The same dll can be found in my Xara Designer Pro X and ProX 11 folders both templop64.dll.