I'm simply trying to illustrate that there is a bit of a paradox that I think is inherent in the language, no matter how it is drafted. If you take murder as the best example, you can claim self-defence to a murder charge and be acquitted, but it's quite clear that you have committed murder. You're just not guilty of the murder.
There are various levels that have to do with the finding that the elements of the offence have been proved beyond a reasonable doubt. Separate and apart from that is the question of whether you should be convicted. That's where the defence comes into play.
There is still an offence there. If there were not an offence, there would be no need for a defence.