Decompiling client and Building

I looked at Gravitir's tutorial on updating client, but I think its too outdated because its version x26.x.x, can anyone teach me how can I build a successful working client. I have decompiled the latest x28.0.2 Crazy client using JPEXS, I want to update the client for myself when x29.0 comes out WITH WORKING & FUNCTIONING ASSETS. How would I go about it? Do I just use the libraries from Gravitir source to build or what do I do? I would love some expert advice.

Update :

I used the x28.0.2 Crazy Client Scripts and added Gravitirs filies over to it. But there is a problem with Modules when I import Webmain or whatever it tries to import it highlights red and then says build configuration not specified. I am desperate for help.

@Gravitir3.14

I'm pretty sure it works fine still. Don't use JPEXS, use the one he said cause JPEXS causes some problems.