ActionScript 2.0 Class Property Problem and Compile Error Display

This happens to me every time when there's a SWF file that comes with packages of ActionScript files and folders, when I convert them to FLAs by using JPEX Flash Decompiler that is in ActionScript 2.0. When I open the converted FLA on any Adobe Flash Professional that I use. I export the SWF files and check the syntax in any ActionScript files and I get a lot of compile errors that are the method, property names, and functions every single time. Even the components ActionScript files from the SWF that I convert to a FLA as well happens. This is mostly the problem that I'm having in ActionScript 2.0, is there really a solution for this or any other way to fix that type of issue here?