Hi,
I encountered this problem around September of last year. I was aware GAE Launcher had been deprecated but the version I had still worked, so I kept on using it till around Aug/Sep when Google stopped supporting 'appcfg.py' commands (GAE Launcher used appcfg.py).
I love the ease of use of a GUI and so decided to build a replacement/alternative -
https://nocommandline.com . I'm looking for early adopters/testers. If you're still missing GAE Launcher, consider giving the tool a trial and give us your feedback.
Cheers