There might be technical problems with the name itself, but the license text explains the intent and refers to the https://unlicense.org/ site which has additional clarification. Proper use as recommended on the site has zero legal ambiguity.
The idea that "BSD0" or "CC0" are better names makes no sense whatsoever. Public domain releases are made by those who do not want the baggage of a BSD or Creative Commons license. Maybe someone in these organizations should talk to someone familiar with marketing and namespaces to come up with a real solution?
The CC0 suggestion is especially ironic since that has not approved. It doesn't actually exist as a legal standard which makes it unappealing.
The OSI, FSF, FANG and other such companies, and the European Union need to get over the idea that they can and even must dictate all aspects of intellectual property ownership as they see fit. My code is not theirs and this is the core issue. My code is mine and thus mine to give away completely free without being encumbered by licensing schemes intended to yield control or profit. That their schemes for control and profit are so out of control that there is no agreed upon or even consistently imagined escape is a sign that they are operating beyond rational limits.