Another update, couldn’t find specific Clout fittings anywhere, though the olives look the same as symmetrical Magura ones but at £9.95 each that wasn’t going to happen 🙃
What I thought was a rubber o ring was actually just the exposed hose outer after the olive had been crimped on, I had a few universal olives in my tool box so thought I’d try one. They weren’t quite the right size, I had to heat up the hose then douse the barb in freezing spray to get it in, and even then it needed some pretty big whacks from a proper hammer, and then the newly expanded hose was too big for the olive to slide over so that needed hot and cold treatment too. Got it all assembled and cranked up tight though and the brake works fine with no leaks, so mission successful I’d say.
TL/DR: universal olives work if you need to shorten the hose, just a right PITA to fit.