I have noticed that there is a Qt-based Texmacs version being developed, which revived my interest in the project.
I did, however, not manage do get Reduce working with Texmacs anymore although I once had understood the communication. Possible reasons are changes in the Texmacs protocol or modifications of tmprint.red to use it for the CSL frontend.
There is Andrey Grozin mentioned as the maintainer of a Texmacs-Reduce interface on http://www.texmacs.org/tmweb/about/authors.en.html.
I assume that Andrey is on this list? I would suggest to provide under trunk/generic the necessary interface code.
Dr. habil. Thomas Sturm
Departamento de Matematicas, Estadistica y Computacion
Universidad de Cantabria, Santander, Spain
Avda. Los Castros s/n, Room 1072, +34 693 251058