I don't really understand this hate against Double Rainboom? It's a FAN-made episode, not an official one. Fans aren't professional writers. It's sorta like a longer comic strip.
Ok, yes Zach is not a professional writer - but it doesn't really take a professional to realise that it wasn't the best idea. The long and awkward gaps in the dialogue, the poor characterization, the poor execution of the script - I could go on.
Saying something is "fan-made so you can't expect it to be professional" is a poor excuse, because there are some pretty well written fanfics out there, and even Snowdrop that aired the other week had a better plot so there is proof that Zach could have done far better.
It leads me to believe that he didn't even get it proof read. There are hundreds, if not thousands of people that could have proof read it for him and suggested little changes. Maybe not massive changes to the plot, but little changed to the dialogue to make it seem more alike to an actual episode - which was the original intention. The crossover should have been much quicker, it shouldn't have taken up a third of the whole episode. It would have been funny as a little joke, but it got far too awkward far too quickly.