Actually, I don’t think that an official release will give you a 100% security. I think there is always a small risk. You might also make a small mistake yourself during the flashing process or whatever.
I tried the unofficial build here and it works just fine. Only encryption did not work for me but neither did it work for the official build of my A5 2017 (but others were able to conduct the encryption, so that might just be me doing something wrong).
Whaterver, I guess there are several people who are using the above mentioned build and reported that it works just fine.