Dear Cem,
 
First of all, thank you for your efforts. I really appreciate this!
 
My version of Composite C1 is different. Mine is 4.2 Update 1.
 
Rem : My WebSite is in WebSite mode not in WebApplication mode. 
 
My development machine is a Windows 10 with Visual Studio 2015.
My production server is a Windows Server 2012 R2
 
Here are the steps I followed:
 
1. I copied all 5 Gleamtech dlls in bin folder on Composite.
2. I added the line code for license in Application_Start of my Global.asax:
 
GleamTech.FileUltimate.FileUltimateConfiguration.Current.LicenseKey = "XXXXX"
3. For testing purpose, I created a webform page test.aspx in the folder /WebSite/Renderers/ with this code behind:
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using GleamTech.FileUltimate;
using System.Web.Routing;
public partial class Renderers_test : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        GleamTech.FileUltimate.FileUltimateConfiguration.RestoreRoutes();
        Response.Write(RouteTable.Routes.Count + "<br/>");
        foreach (var _RouteItem in RouteTable.Routes)
        {
            try
            {
                var _r = (Route)_RouteItem;
                Response.Write(_r.RouteHandler + " | " + _r.Url + " | " + _r.Constraints + "</br>");
            }
            catch { }
        }
    }
}
Result of execution on my development machine:
 
1. With the original GleamTech.Core.dll, I received this error : 
 
Unable to cast object of type 'Composite.Core.Routing.Pages.C1PageRoute' to type 'System.Web.Routing.Route'. 
2. With the new version of the dll, no error. Here is the result:
 
17
GleamTech.Web.HttpHandlerRouteHandler`1[GleamTech.Web.ResourceHandler] | resource.ashx/{*pathInfo} | System.Web.Routing.RouteValueDictionary
GleamTech.Web.HttpHandlerRouteHandler`1[GleamTech.DocumentUltimate.Web.DocumentViewerHandler] | documentviewer.ashx/{*pathInfo} | System.Web.Routing.RouteValueDictionary
GleamTech.Web.HttpHandlerRouteHandler`1[GleamTech.FileUltimate.FileManagerHandler] | filemanager.ashx/{*pathInfo} | System.Web.Routing.RouteValueDictionary
GleamTech.Web.HttpHandlerRouteHandler`1[GleamTech.FileUltimate.FileUploaderHandler] | fileuploader.ashx/{*pathInfo} | System.Web.Routing.RouteValueDictionary
GleamTech.Web.HttpHandlerRouteHandler`1[GleamTech.ImageUltimate.Web.ImageHandler] | image.ashx/{*pathInfo} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | Composite/{*pathInfo} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {resource}.axd/{*pathInfo} | System.Web.Routing.RouteValueDictionary
Composite.Core.WebClient.FunctionBoxRouteHandler | Renderers/FunctionBo{x} | 
Composite.Core.WebClient.TemplatePreviewRouteHandler | Renderers/TemplatePreviewImag{e} | 
System.Web.Routing.StopRoutingHandler | sitemap.xml | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {language}/sitemap.xml | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {language}/{urlTitle}/sitemap.xml | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | Renderers/{*pathInfo} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {*all_css_aspx} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {*all_js_aspx} | System.Web.Routing.RouteValueDictionary
Composite.Core.Routing.PageNotFoundRouteHandler | {*url} | 
On the production server:
 
1. I copied the Gleamtech dlls in the bin folder of Composite
2. I copied the test.aspx in /WebSite/Renderers/
3. Add the line code for license in Global.asax
4. With the original GleamTech.Core.dll --> same error as development environment 
5. With the new version of dll, Here is the result:
 
12
System.Web.Routing.StopRoutingHandler | Composite/{*pathInfo} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {resource}.axd/{*pathInfo} | System.Web.Routing.RouteValueDictionary
Composite.Core.WebClient.FunctionBoxRouteHandler | Renderers/FunctionBo{x} | 
Composite.Core.WebClient.TemplatePreviewRouteHandler | Renderers/TemplatePreviewImag{e} | 
System.Web.Routing.StopRoutingHandler | sitemap.xml | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {language}/sitemap.xml | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {language}/{urlTitle}/sitemap.xml | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | Renderers/{*pathInfo} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {*all_css_aspx} | System.Web.Routing.RouteValueDictionary
System.Web.Routing.StopRoutingHandler | {*all_js_aspx} | System.Web.Routing.RouteValueDictionary
Composite.Core.Routing.PageNotFoundRouteHandler | {*url} | 
So, it seems that the call of the method GleamTech.FileUltimate.FileUltimateConfiguration.RestoreRoutes() have no effect. The 5 FileUltimate routes are still missing.
 
One more indication:
 
If I clear all routes (RouteTable.Routes.Clear()) before calling (with the original Core dll)
GleamTech.FileUltimate.FileUltimateConfiguration.RestoreRoutes();
In development : I have the 5 FileUltimate routes created.
On production :  No route.
 
Thank you again in advance for your response.
 
Kind regards.