First of all, Sol, I asked you "Please show us where the EU predicted and explained the singing comet.", and then you answer me with a simplistic listing from the electricuniverse site, which has nothing about any EU predictions, only some, mostly misinterpreted, one-line claims. Let's go through them, shall we?
Comets
Well don't believe everything that Ian writes down on his website. Some of the finer points of the abstracts (and possibly the full papers) seem to be lost in his simplified listing about "Extraterrestrial (cosmic) electricity" / Comets.
Comet nuclei charge electrostatically.[37]
Yes, they can have an electrostatic charge, even opposite signs depending on which side of the comet you are. And to quote the abstract of the paper [37] "It is shown that beyond a heliocentric distance of about 5 AU, a water-dominated cometary nucleus is not shielded from either solar UV radiation or the solar wind by a protective atmosphere. As a result, the nuclear surface gets electrically charged, the surface electric potential varying from small positive values near the subsolar point through numerically moderately large negative values near the terminator to numerically very large values on the dark side.
We are well beyond that stage with 67P/CG. Sometimes it helps reading up the stuff that you link to.
Comet dust charges electrostatically causing it to levitate from the comet surface.[38]
Yes, that may happen when the surface is charged, but see comment above, by the same author.
Cometary current system: plasma tail streamers separated by a neutral current sheet, has a total current exceeding 10^8A.[39]
What the total current may or may not be is unimportant, because that is dependent on how big the structure is. It may seem a lot 10^8 A, but it is the current density that is important to see whether it is big or not. Anyway, that current must exist, because it is between a region of oppositely directed magnetic field, just like in the Earth's magnetotail.
Cometary plasma tails, generate magnetic fields and electric currents of up to a billion Amp.[40]
No, that is NOT what the paper says. Cometary plasma tails DO NOT generate magnetic field, the plasma (or better ion) tail is made of magnetic field that is draped around the comet. To quote the abstract: Due to the folding of the interplanetary magnetic field into the tail as a comet sweeps through the interplanetary medium, the magnetic field in the tail can be built up to the order of 100 gammas at a heliocentric distance of about 1 AU. This folding of magnetic flux tubes also results in a cross-tail electric current passing through a neutral sheet. Then it starts to discuss about "streams of enhanced plasma density" but as I do not have access to this paper I cannot further discuss this, but the abstract is at least vague about what is being proposed.
Cometary atmosphere feature electric currents.[41]
This paper discussed a kind of "substorm" at currents. I would not have called it "atmosphere" but rather "magnetosphere". If a current (the cross tail current) gets disrupted the current needs to find another, usually field aligned, path to close itself again. This may happen in the case of a tail detachment event.
Cometary aurora due to "current discharges into the atmosphere from the tail.[42]
Don't think you will see northern lights on a comet. Indeed, the Houpis & Mendis (1981) paper says "cometary aurora" what is meant here is an enhanced ionization rate near the comet, driven by currents. Normally, aurora is the excitation of molecules, which return to ground state emitting a photon. So, although it is a nice term, it has nothing to do with planetary aurora as we know them.