The Enceladus-Saturn system is probably one of the most studied systems in the solar system, thanks to the persistent presence of the Cassini-Huygens remote sensing mission. They have acquired enormous amounts of data about the bodies themselves and the environment in which they exist. That said, it is not surprising that their interpretations of those findings do not always accord with the EU perspective. Nonetheless, good observational work is being done daily, and the imagery is widely available to the public. Images (radar, optical, UV, radio and IR) don't make the whole picture, of course, but Cassini has a suite of other instruments that sample and classify (or "taste" as Ms. Porco chooses to call it) the local environment by means of plasma spectrometry and magnetic field intensity meters.
They have certainly flown through ionized
material surrounding Enceladus, in particular the south polar jets and its thin ionosphere and the plasma torus within which Enceladus's orbit lies. They have detected sodium, chlorine, and hydroxyl ions - hence the terms "saltwater" - which those would become if they were in a less energetic plasma environment and recombined to create neutral atoms. But in the low pressure and ionized condition, they likely don't, at least not in large numbers. The rate at which water seems to be machined (electric discharge machining, EDM, via a large current flow through Enceladus's near-pole regions), which is called "mass-loading" seems to show a rate of water introduction to the ionosphere and plasma torus which would account for the fraction of water ostensibly measured in Saturn's atmosphere, and not the other way round. However, mass loading might be a 2-way street where water vapor on Saturn might well be accelerated (once ionized) toward Enceladus as well as the other way around. I for one couldn't comment on that, and I doubt that they have measured that small a detail.
They also know that there is an electric circuit, a current, which runs via a "magnetic flux tube" (a Birkeland current in our terminology), delivering charged particles to Saturn's polar aurora, creating energetic hot spots visible in ultraviolet light which are the same as the polar hot spots created in Jupiter's auroras by Io and three other moons. The return circuit is not identified, although some scientists have speculated that it may be via Saturn's equatorial current sheet (about which I know virtually nothing yet). Try googling "Enceladus magnetic flux tube" and look at the stuff that pops right up. Sparky, even your impaired box should be able to manage this.
I have e-mailed Ms. Porco asking if she could get the Cassini to investigate the possibility that there is a comparable "flux tube" in the southern direction between Enceladus and Saturn, and if so it might constitute the return side of the circuit between the two bodies, but no response. Those orbital missions are probably planned years in advance, and citizen input is unlikely to be considered, IMHO.
No evidence of hot spots has thus far been presented, in Saturn's southern
aurora, so it is still unknown whether or not those have even been looked for, or if it is still unreported because further research is being done on it, or none have been found. If you don't look, of course...
That a current flow is present in the "tiger stripes region" near Enceladus's south pole seems obvious. Tidal heating is not strong enough to account for either the "geysers of salt water" or the amount of "anomalous" temperature rise found near the south pole, many times in excess of what they had expected. Joule heating
(James Joule, 1841) caused by electric currents moving through resistive material in the moon's crust or interior could readily account for such heat formation, however, depending on the telluric (underground) current strength. I have asked for the current value (amps) or the power (watts) found by Cassini in the northern "flux tube", to no avail. I'm sure it's in there somewhere, though. The Cassini sites have covered most of this stuff pretty thoroughly, although most of the interesting papers remain behind the ol' paywall, as usual. Publicly funded and privately retained for sale, of course.
In plasma deposition or removal, the plasma need not be 100% ionized - plasmas can be formed with less than a percent of the particles being charged,, but as long as there is sufficient voltage, the charged particles can be energetic enough to entrain, and possibly ionize, neutral particles in order to yield a large mass flow onto or away from a body. As Enceladus is measured to be a charged body, and it is moving through Saturn's not insignificant magnetic field, electric currents of charged material must
be set up and flow in some circuit through the polar (and other) circuitry.
From the EU perspective this seems both obvious and elegant, the simplest way to transmit and dissipate the power generated by a moving charged body in a planetary magnetic field.