docs say loc-randomise: should act like loc-offset: (which does work). Using OtherDrops:2.8b.334

just to be sure, I also tried loc-randomize...

Cool, will look into that. Got some new ideas too - perhaps allowing loc-randomise to use a range (if I didn't do that already) somehow to set a minimum distance from the player and perhaps search for a required block (eg. air).

the docs mentioned loc-randomize should do range just like offset. I would simply find it easier to set a radius or radius-range, rather than x/y/z. And yes, they should spawn safely...