I think this is the wrong place for your question. But I’ve had to set lists of things to their index in multiple situations in the past. Bulk AND recursive backend workflows were a pain, and stupidly costly for what would otherwise be a lightning fast script in javascript. Someone found a solution and it works a million times better than anything else. Check it out in this thread, and if you have any questions about it, ask there. Hope it helps you!
It works on the front end, so if you dont NEED that, you can always set yourself up a little admin page with the data set you need there in an RG, and run it with a button/workflow.