Yea unfortunately there is no way to drop the level of any specific item down to a specific SRS level. Best you can do is move specific sets from Burned all the way down to Apprentice.
I just recently used the [Userscript] Burn Manager (Review / Resurrect / Retire) script to downgrade 1000+ “Burns” back to “Apprentice” level because of how slow I go. Instead of resetting my level progress entirely, I just wanted to put them back into the queue. So now it’ll be a ton of work to go through 1500 Apprentice items, but it’ll eventually even out since any that I have truly “burned” will quickly rise through the SRS levels while those I didn’t truly burn will come back into scope.
However, what I really would like is just a way to manually set them to never be “Burned” and just have things stay at “Enlightened” or on the last (6 month I think?) 4 month (thanks @seanblue) SRS cycle so that they just perpetually reappear ever so often. I know I could offload things to other places like Anki or KaniWani to do that I guess… but for now I haven’t.