Yes, comparisons to other tools are planned.
In the list (feel free to complete it) :
If some expert on any of those tools is available to help me make the more honest comparison possible, it'd be amazing.
ciao, bonobo might be something that i need as a pythonic replacement of xslt, thus i consulted the docs to get a grip of it. i didn't find out whether it fits, but i found some questions that would help me to figure it out. maybe that helps you when you update the docs (which i would strongly suggest as the library looks promising, but it's hard to judge if it'd be suited for a task.)
on a sidenote, what the heck is marketing-automation? how would that make the world a better place?
Not easy to understand what you're looking for. You're saying "pythonic replacement of xslt", and bonobo can transform xml into something else (or into another xml). Which sounds like what you say, but not certain about your use case and whether or not it would be an idea worth considering.
I'll try to answer your questions here, even if this would maybe suit more a discussion on slack than comments in another ticket. I'll consider your questions for a future F.A.Q. section in the doc (along with others, of course)
What exact facilities are available to control the evaluation logic of a graph?
Can a graph contain another graph?
How would one access contextual data from a transformation? / are there parameter injections like pytest's fixtures?
Are there yet any concepts how to process trees, like xml?
How is a plugin distinguished from a python import in a module that contains transformation callables?
On a sidenote, what the heck is marketing-automation? how would that make the world a better place?
I hope it answers your questions, if not, let's have a chat on slack so I better understand your points.