The Transform window and the Transformer object in the Environment are very cool!
At first they can look intimidating, but once you become familiar with them are very powerful ways to edit MIDI Events.
The TNT1& especially 2 series do look in depth at creative ways to use Transformers and environment objects.
Probably the best tutorial is Steve H's Logic Masterclass 1:
Where there are more than 10 videos dealing with the Transform window alone.
It's difficult to explain it here...
Basically there are two horizontal areas Conditions and Operations. Top area is for incoming MIDI data, bottom area is for what you want to transform it to.
First column deal with the type of MIDI data (e.g. Notes/CC/Fader). The top specifies which is to be transformed the bottom what you want to transform it to.
... and the columns continue in this vein.
Hope that helps :)