Sorry 1991 but you very clearly DO NOT know the law!
Being found guilty either by plea or by trial is still a conviction. Most sentences are not jail terms, fines ,suspended sentences and community service are a lot more common than prison sentences, but they are still sentences for a criminal conviction. Your BF does have a criminal record !
If a witness makes a statement they CAN NOT withdraw or 'drop' that statement. This is a very common mistake we hear it all the time. If a witness makes a statement and later realizes the statement was wrong or they need to change details they can only make another statement saying why the first one was wrong. The first statement and any other later statements are still evidence and can be used in court. The witness can expect to be cross examined in court about why they made a second statement that was different to the first one.
We are NOT judging your BF, the jury will do that when his case is heard in court. All you, he and his solicitor can do is to make sure all the facts have been disclosed to the court and to his solicitor. Solicitors DO NOT withhold information. His solicitor will tell your BF all the information but it is your BF who is on trial not you. The solicitor does NOT have to tell you anything as you are not his client your BF is. The solicitor in fact is banned from giving you any information about the case unless his/her client , your BF, has given permission for you to be told. You have admitted you do not actually know what happened in the house, you only know what your BF has told you. Again as you say, your BF was knocked unconscious and that will affect his memory of the events. He may not remember what actually happened or he may be confused and get things wrong. Confusion is normal after a head injury.
When this case comes to trial the jury WILL NOT know anything about your BF's previous history, convictions,statements or warnings. Only the judge knows that and will use the information to decide on the sentence if he is found guilty.
Please try to remain calm and focused on what you can do to help your BF.
Making wild accusations that the CPS are corrupt and everyone is against him will not do any good.