Maybe in that case it would be possible to show a message to know that rc.exe does not exist.
Did you try the "Be verbose" option?
Yes, I agree. Indeed, I used verbose mode, but got no alert message whatsoever.
Anyway, not that I want to make a big thing of it, if I may suggest, the Ultimate++ Win32 Installation Guide could include another bullet point indicating the need to mark the tools section in the SDK installation wizard. This could be especially supportive to new U++ adopters.