I made a TechReborn's recycler hoping to recycle junk into something useful.
I was able to get a scrap from it despite scrap not showing neither recipes or usages in REI.
However, it's unclear how can I further proceed to crafting an actually useful scrap box from it (doesn't show a recipe either). Default recipe from tech reborn wiki doesn't seem to work. Recycling is not mentioned in questlines whatsoever, at least as far as 3.5 stage goes.

It this intentional? Is there an other recipe? If not, is there a way to fix that with some config edits on the server side?

Thanks!

Not just now, but the next version will have scrap and it's purpose adjusted back to what you're expecting, we've since been able to update the loot tables.