I have not tried them in a long time.
There are details of some of the stuff I did back then:
Robotis Dynamixel Shield code does not compile - Classic / UNO R4 Minima - Arduino Forum
I believe Robotis maybe put hack in around the issue of LED_RED defined, if not
the hack is shown in either the thread above or the links in it.
There are/were issues with the UNO R4 software implementation of the hardware Serial ports, like there is no TX buffering and the like, that I had a PR to rework a lot of it. I believe others have as well, but not sure if any changes have been incorporated.