Welcome to the Community Dawn:
We are happy to have you.
I don't think anyone could gruantee no cracking of the plaster but I think the pneumatic driver would be more safe than the manual nail gun which uses the large mallet to drive the nails. The air gun doesn't seem to shake everything because the pressure is all on the nail; while the mallet gun has to be hit hard enough to drive the nail the first time and that takes quite a whallop.
In a 90 year old house the lath that holds the plaster is the small wood strips with the plaster bulging through the cracks and having a large anchor on the back side. Whereas, the newer lath is 2' x 4' pieces of sheetrock. So, I would think the older method has a better chance of holding than the modern method; but still there is no gurantee. Wow, doesn't that sound like a politician's answer?
The best I can recommend is to use glue and screws on the plywood, being careful not to drop any pieces of the plywood during installation, which would serve to stiffen the ceiling/floor and then give the pneumatic gun a try. Make sure there are no bundles of flooring dropped and no large stacks of it in a concentrated area (which would flex the ceiling/floor).