RE I was thinking about python script
I just added this feature to an app I am writing in C# and it was actually quite easy to do. What I did was take a simple 2-clip project and add a transition between the clips. I then checked out the resulting MLT file and figured out what is needed for each transition. I can now add hundreds of transitions in C# in just a few seconds. It should be a doddle in Python as well.
This link is a good intro to MLT file format and helped me a lot.
https://www.mltframework.org/docs/mltxml/