1) Steve Grimes once stated that under some conditions, ultrasonic cleaner can etch a lens, so, either keep your glass outta the the fluid or see if SK Grimes folks can qualify that coment.

2) I once had an Agfa folder with the front cell stuck so badly I gave up on all the tools I had & threw the ...I'm tryign to get my story right...it's been a while...I may have just put the front cell assembly in , and not the shutter. I think I used an aerosol dichloromethane or similar for the shutter (I learned don't do that outside in humid summer weather...the expanding gas will chill and condense water so badly out of the humid air your (camera) parts will frost heavily.

I worked somewhere that misused their ultrasonic cleaners...they put solder flux 'safety solvent' in ...a non-flammable hydrocarbon, for degreasing aggressive lubricants. I put that lens in for I think 10 minutes. When I came back, not only was my front cell unstuck, all the lens elements were unscrewed and most of the paint was gone too! I was kind of startled. The brass underneath was a weird military olive drab.
I greased the lens cells & moved on...

As far as I know, you're not supposed to use non-aqueous solvents in such cleaners, for many reasons, one of which is improper containment of vapors...you don't want such chemicals evaporating into your breathing space.

There are enough proper solutions available for the average job.

But you may consider loosening of shutter screws as a hazard to watch for. Maybe I'm talking from my armchair and people do it all the time without trouble. The one I used was pretty hefty.Maybe it would heist diamonds from rings put in there too.