As a Sociologist I may contribute some thoughts. Emirbayr/Mische (1998) define human ageny as “the temporally constructed engagement by actors of different structural environments - the temporal relational contexts of action – which, through the interplay of habit, imagination, and judgment, both reproduces and transforms those structures in interactive response to the problems posed by changing historical situation“
Habit as sedimented experience, judgements as answers to actual problems and imagination as goals should be included in the experiment. I may have overread it, but is it planned to let the code changig happen based on problems the creatures experience? If they experience problems in the dimensions of intelligence like musical-rhythmic, interpersonal etc., they may be forced to build gerneral solution patterns.
Edit: As I think further, human intelligence is based on communication, e.g. collaborative problem solving. So when creatures can communicate they could be presented tasks which require collaboration, like hunting.
BTW this is a great idea!
Best regards, Olivier