I had been struggling for months, trying to get a pre-existing form (legacy application from a different CMS) to work within my Joomla! site. Then, lo and behold, I stumble across Sourcerer. Your extension was a life saver. Now, not only do I have the form (form to email app) working, it works as expected. I've also used it to help with creating a custom database search within the site.
I had a little bit of confusion the first time I tried to use it, but realized the problem was of my own making. Once I cleared that up, I had absolutely no trouble with it. It does help to actually read (not skim!) the instructions and actually follow them. Works like a charm with TinyMCE - button and all.
Thank you for creating this gem and sharing it.