It is plausible and no big suprise. It has long been known that combinations of some alcohols, salts, acids etc can have a catalytic effect on other materials and processes. It’s like saying that long term heating of vegetables in lightly salted water can miraculously result in vegetable soup.
Not really plausible. Superconductivity has a specific kind of meaning and while immersing something in liquid does improve its conductivity because of factors like ionic conduction, it seems implausible that the kind of superconducting state found in known materials using known processes is generated by this method. More detailed research should bear out what’s happening.