In the UK we have had an IMC ratting for many years which allows flight in IMC and to make instrument approaches, albeit to a higher DA. Under EASA, that became the IR(R) which is to be superceded by the BIR. It would be criminal to lose the IMC/IR(R) in favour of the BIR which requires more training and instructors with full IRs. I can see no reason why an instructor with a BIR (if they get one) shouldn't instruct for that rating - why should they need a full IR?