Update Enterprise Custom Fields related to Enterprise Resources in PWA Online

[Service CSOM]

I have a requirement to update Enterprise Resources in Project Online based on a condition and also need to update the Enterprise Custom Fields of Entity='Resource' related to it. I'm not able to find a connection between the two. What I have done so far:

1. Fetched Enterprise Resources from PWA. Enterprise Custom Fields related to Enterprise Resources are: Office, Level, SupervisorID, Division, Status, Supervisor, DepartmentNumber and LaborCategory  

using (ProjectContext projContext = new ProjectContext(projectUrl))
{
    SecureString securePassword = new SecureString();
    foreach (char character in password.ToCharArray())
        securePassword.AppendChar(character);

    projContext.Credentials = new SharePointOnlineCredentials(username, securePassword);
    enterpriseResources = projContext.LoadQuery(projContext.EnterpriseResources);
    projContext.ExecuteQuery();

    if (enterpriseResources.Count() > 0)
    {
        foreach (EnterpriseResource resource in enterpriseResources)
        {
            if (!string.IsNullOrEmpty(resource.Email))
            {
                var enterpriseResource = projContext.EnterpriseResources.GetByGuid(resource.Id);
                var enterpriseResourceCustomFields =                     enterpriseResource.CustomFields.GetByGuid(resource.Id);
                enterpriseResource.Email = "sreedevi@test.com"; //Email
                enterpriseResource.Name = "Sreedevi H"; //FullName

                projContext.EnterpriseResources.Update();
                projContext.ExecuteQuery();
            }
        }
    }
}

I have tried below code to fetch the fields mentioned above but not able to fetch Enterprise Custom Fields Related to it:

foreach (EnterpriseResource resource in enterpriseResources)
{
    if (!string.IsNullOrEmpty(resource.Email))
    {
        var pId = Guid.Parse("a5c8801f-d505-e811-a745-b0359f8878e9");
        var customProject = projContext.LoadQuery(projContext.Projects.Where(p => p.Id ==                 pId).Include(
                p => p.Id,
                p => p.Name,
                p => p.IncludeCustomFields,
                p => p.IncludeCustomFields.CustomFields,
                P => P.IncludeCustomFields.CustomFields.IncludeWithDefaultProperties(
                lu => lu.LookupTable,
                lu => lu.LookupEntries)));

        projContext.ExecuteQuery();

        foreach (PublishedProject pubProj in customProject)
        {
            var projECFs = pubProj.IncludeCustomFields.CustomFields;
            Dictionary<string, object> ECFValues = pubProj.IncludeCustomFields.FieldValues;
        }
    }
}

Any idea to find a relation between resource and custom fields will be helpful.