If you can build a magma-safe pump stack, you can likely build the described lava sprinkler.
It's just drawing it from the source, pumping it up the stack and pushing it out at (ideally) 2 Z above your targets.
Armok help you if there's grass though, because such a thing will light your entire embark level on fire, and spread.
Personally? I would build a contained/dug magma-filled hallway or even the old "pressurized magma above a door" trick, with multiple ingress paths and grated surrounding floors for drainage.
In my experience, the challenges when dealing with magma automation and/or magma traps have been related to:
- finding a magma source that refills fast enough
- possibly building a cistern large enough
- having a drain that's large/fast enough
- non-evaporating magma blocking enemy pathing for extraordinarily long durations
- buggy enemy & ally pathing over tiles on which magma has evaporated
- partial (1/7) versus complete (7/7) magma depth, on the target(s)/tile(s)
- arranging power/axles/gears to be adjacent (vertically/horizontally) without compromising access/security/pathing
- doors remaining open after enemy vaporized by magma behind or above the door
- goblinite item movement and retrieval
- teleportation/pushing of 'swimming in magma' enemies through fortifications full enough to permit magma flow, but causing no damage to the enemy
But happily, all of those problems have solutions.