I resolved most of the warnings for compilation and decided to try the modern install. Towards the end of the install I saw this page:

All the languages had a link to the RTF file. Eg:

Name: "English"; MessagesFile: "compiler:Default.isl"; LicenseFile: "..\..\Inno\l.eng\LicenseEnglish.rtf"; InfoAfterFile: "..\..\Inno\l.eng\InfoAfterEnglish.rtf"
Name: "German"; MessagesFile: "compiler:Languages\German.isl"; LicenseFile: "..\..\Inno\l.deu\LicenseGerman.rtf"; InfoAfterFile: "..\..\Inno\l.deu\InfoAfterGerman.rtf"
Name: "Italian"; MessagesFile: "compiler:Languages\Italian.isl"; LicenseFile: "..\..\Inno\l.ita\LicenseItalian.rtf"; InfoAfterFile: "..\..\Inno\l.ita\InfoAfterItalian.rtf"
Name: "Spanish"; MessagesFile: "compiler:Languages\Spanish.isl"; LicenseFile: "..\..\Inno\l.esp\LicenseSpanish.rtf"; InfoAfterFile: "..\..\Inno\l.esp\InfoAfterSpanish.rtf"
Name: "Polish"; MessagesFile: "compiler:Languages\Polish.isl"; LicenseFile: "..\..\Inno\l.plk\LicensePolish.rtf"; InfoAfterFile: "..\..\Inno\l.plk\InfoAfterPolish.rtf"

Why is it not working?

I commented out the skinning software and it made no difference. Nor did using the classic wizard. If I use version 5 and compile and execute:

So version six seems broken here for InfoAfterFile?

Sample Script

; Script generated by the Inno Setup Script Wizard.
; SEE THE DOCUMENTATION FOR DETAILS ON CREATING INNO SETUP SCRIPT FILES!

#define MyAppName "My Program"
#define MyAppVersion "1.5"
#define MyAppPublisher "My Company, Inc."
#define MyAppURL "http://www.example.com/"
#define MyAppExeName "MyProg.exe"

[Setup]
; NOTE: The value of AppId uniquely identifies this application. Do not use the same AppId value in installers for other applications.
; (To generate a new GUID, click Tools | Generate GUID inside the IDE.)
AppId={{3E02F6B8-8680-4878-9AAE-BBC7B94B56C4}
AppName={#MyAppName}
AppVersion={#MyAppVersion}
;AppVerName={#MyAppName} {#MyAppVersion}
AppPublisher={#MyAppPublisher}
AppPublisherURL={#MyAppURL}
AppSupportURL={#MyAppURL}
AppUpdatesURL={#MyAppURL}
CreateAppDir=no
InfoAfterFile=D:\TestDocument.rtf
; Uncomment the following line to run in non administrative install mode (install for current user only.)
;PrivilegesRequired=lowest
PrivilegesRequiredOverridesAllowed=dialog
OutputDir=D:\
OutputBaseFilename=mysetup
Compression=lzma
SolidCompression=yes
WizardStyle=modern

[Languages]
Name: "english"; MessagesFile: "compiler:Default.isl"

You will need to use WordPad and create a temporary RTF file. Or use the ZIP I put in the comments.

I have raised this bug on the official newsgroup channel for InnoSetup.

Any subsequent discussion will happen there about this issue.