The pair of males on the left are having anal sex; the next pair up seem to
be having less-penetrative enjoyment;
the third corbel from the top right is an acrobatic female similar to one on a window of the apse.
Strange goings-on !
The Collegiate Church of Cervatos is the subject of a study by Glenn
W. Olsen.
Various sins as listed in Penitentials and illustrated on Spanish corbels
can be seen at :
http://blogderomanico.es/07-los-catalogos-de-pecados-de-los-penitenciales
(in Spanish)