I have not been following this thread so if this has been brought up my apologies. But I will relate what happened to a friend of mine.
He built a pair of Electrostatic speakers with integrated transformerless (iirc) tube amp, that appeared in the Audio Amateur. They sounded quite good.
Later he and his wife moved away but I had a business trip and visited them. The Electrostats were gone replaced with some panels similar to magneplanars (they weren't magneplanars but a cheaper generic clone which I forget the name of)
I asked my friend "Wha Hoppen to the Electrostats???" (which he had worked very hard on beating them into submission and was very proud of them , and they did sound good until they suddenly hit the stops.)
"I saw Eliot poking around back there" (Eliot was their toddler)
You probably don't want electrostats around small chilluns or certain pets. jmo
Direct-driven/transformer-less ESL's can be especially dangerous because the potential lethal drive current is carried through exposed speaker cables, likely not designed for that much voltage, and that makes it dangerous even if the remainder of the speaker is safely built. Transformer driven ESL's can be dangerous too, if the stators or step-up transformers are exposed. Most DIY ESLs use poorly insulated perf metal stators, inadequate wiring, and would not pass UL testing and approval, as commercial speakers must.
That said; it isn't difficult to build a safe ESL-- it just takes a bit more effort and expense. My own ESLs use insulated wire stators which I can touch without danger while they are playing, and front & rear grill covers offer an added level of protection. The speaker cables don't carry lethal current, drive cables are insulation-rated for 30kV, and the electronics package is totally enclosed in an impact resistant, high dielectric strength polycarbonate cover. Even so; if I had toddlers or pets, I would secure the magnetic grills with straps so that they could not be removed. That's what it takes to build a safe and reliable ESL.