@Gozo
Just a note from my practice experiences, 1000 practice shots won't nearly be enough. I've done well over 10,000 BH loops vs backspin and it's just beginning to become useful in games!
Also, 70% success rate in practice is not nearly enough. Success rate drops significantly in games. 70-80% will easily become 40-50% in real games. That means your loop attempts will lose you more points than they win. You need 90+% success rate in practice doing something simple as the drills others have mentioned (i.e. serve, push, loop), assuming you're focusing well like it's a game and your shot is not meant to outright win the point.
LOL, I did at least 200k practice bh loops vs backspin before I accepted it would never be good and switched to pips bh. 1000 is like one or two days worth. I trained that stroke for four years and still gave up after.
About success rate dingyibvs is right, BUT, only if you are playing matches to win instead of to practice. To quote Brian Pace 'nobody cares how many practice matches you win.' You will make progress so much faster if you mentally assign every match to either competition or practice categories. If it is comp just try to win however you can. And when it is practice, do the strokes you want to learn. If your success rate is 20% and you get slaughtered, WHO CARES? It was practice.
I am volunteer coaching five players at a local club who are roughly your level. We get enough training time in a week for each of them to have about 30 - 40 minutes with me. So I told them if they only train that time maybe in a year they will learn a new skill. If they also use the 7ish hours of matchplay we get for training instead of serious comp, that learning time gets cut to 3 months or so. Their choice.
And about your fh loop, the biggest issue I see with these players is that they still bh push from the fh side, or now sometimes bh topspin from the fh side. That's not the problem, but they don't reverse their feet back to a fh stance, or not quick enough. So they lock up their own body rotation and can't play a good fh topspin. There is a negative feedback loop in this where they can't play the practice fh in matches and lose confidence, and lack of confidence makes their fh tighter and worse. But it all comes from the feet. Maybe if your coach thinks it is a good idea, try a drill where you push one ball with bh from your fh side, he pushes back to your fh and you turn around and play a proper loop. That seems more game-relevant than just looping fh vs backspin against multiball where you always have your feet right because you pre-decided to loop it.
Does that make sense?