It is being actively maintained. More important, IMHO, would be if they ( I think it is Chris Hanson these days) would greatly improve some of the documentation. For quite a few things you need to read source code. There is not much for beginners to get started with IMO. Also I think there was a way how some guy got it to work on the M1 Apple. It may have been through a VM however, IDK. As for edwin, I was under the impression that one was left behind years ago. Not sure if it is good enough for what you need (I never used edwin so I don't know at all) but there is Geiser. But I also kinda of agree, compared to other implementations, MIT Scheme seems to have lost some steam. Chicken and Guile for example seem more practical and accessible.