[At long last I might have a headcanon for what the liquid samurai sound like. Well, in their ‘natural’ voices/sounds.
You can skip to 0:25 for when the voice starts to be distorted. They sound staticy and a bit electronic. Some of the rougher first gen Pokemon cries also work.
Finally Spiritomb’s cry is maybe among the more clearer sounds they can make.
Just think distorted crystal/glass noises/hums and crashy static. In their home realm their voices and sounds might be different because the workings of that world are what they are adjusted too and sound might travel differently. I’ve yet to figure out how they might sound if they are making an effort to communicate with a Valley dweller. Most of their communication between one another and the Enchantress is telepathic, but I could see them emitting these strange cries if the situation calls for it or presses them beyond simply telepathy.]