I agree that "opcode" is an inaccurate use of the term for score events, 
but it is not like this was just a Csound error, it goes way back in 
MusicN time.  I am not saying that it shouldn't be changed simply because 
it already has an established meaning, but that it will be difficult 
because there is already a large group of users who already use the term 
opcode to refer to score events.

It is not even a good word to use for orchestra function calls; I guess 
the whole idea was that Csound orch was a "patch" language that 
non-programmers (whatever they are) could easily learn.  But I suspect 
that Csound users who build new instruments are probably programmers 
anyway, i.e. they also program in conventional programming languages.  
The other main group of Csound users are those that create new scores 
that use existing instruments. (I have never actually met anybody who is 
a pernmanent member of this group.  It seems to be more of a phase that 
people go through when they first learn Csound - or something that people 
who build instruments might do when they come across a new technique.)

Why not use the term function to refer to ...er... the function calls in 
the Csound orch and a generic term like statements to refer to everything 
else?