I think DrRacket also has something like this, but it shows lines between identical variables instead of using colors.

Seems dead for many years already.

How many updates per month are you expecting for a package like this?

Multiple times a day, like radare2. Seriously, if there is no activity in 6 months - then the project is dead.

This is a lexical highlighter that tries to highlight similar, but different text differently. There's a point in time where there are no new features necessary.

radare2 is a portable reversing framework. I can't think of 2 projects more dissimilar. Perhaps you were thinking that the highlighter actually did something other than color text in an arbitrary way? Can you give an example of something that you would expect to change about it, especially at the rate of multiple times a day?