From Oxford SuperLex, for "adscripto:

adscripto2 -ta m, f (RPl) (en Arg) graduate student who also
teaches in the department; (en Ur) person who carries out
certain administrative tasks in a secondary school

cátedra f (en la universidad) professorship, chair;

[Note: in the US, this is equivalent to a **full** professorship--the top rank for university instructors]

catedrático:

Again, this is either a "full professor" or someone who has been named to a funded "chaired professorship": a chaired professor.

Here are a few examples of "chaired professor" I picked up using Google (Google found 1,200 sites with the term):

Stanley Sandler named engineering's first chaired professor
Vol. 19, No. 27. April 13, 2000. Stanley Sandler named
engineering's first chaired professor. ...
www.udel.edu/PR/UpDate/00/27/stan.html - 4k

Stanley Sandler named engineering's first chaired professor
Stanley Sandler named engineering's first chaired professor.
Stanley I. Sandler, Henry Belin ...
www.udel.edu/PR/UDaily/Sandler041400.html

Lally School Names New Chaired Professor
Lally School Names New Chaired Professor. Shikhar Sarin,
a scholar in the field of new product ...
www.rpi.edu/dept/NewsComm/Review/sept96/sept20/lally.html

Michael Shur Becomes Chaired Professor
Review Nov. 22, 1996, Michael Shur Becomes Chaired Professor. SHEILA NASON. Michael S. Shur ...
www.rpi.edu/dept/NewsComm/Review/nov96/nov22/shur.htm

The confusing part about translating the Spanish term is that a cátedra/catedrático falls about halfway between the two meanings in English: someone whose rank is "catédratico" occupies a chair, **but** the chair is not specially funded, the way such chairs are in our own university system. My recommendation is that you go with "full professor" unless the "cátedra" actually has a name attached to it.