Perhaps the original source of the alleged translation is the IMDB. If I'm not mistaken, isn't IMDB similar to, but not a duplicate of, the Wikipedia, in that it accepts user info submissions? Just a thought.
I looked this up in both Harry Potter: Film Wizardry by Brian Sibley and Harry Potter: From Page to Screen by Bob McCabe, both definitive books on the Harry Potter movies (seriously, they are huge and incredibly detailed in both images and information.). Neither mentioned the phrase More or less human, at least not that I could find (I'm relatively competent when it comes to finding Potter info.). Anyhow, the McCabe book says: Director Alfonso Cuarón suggested the Azkaban tattoos, which represent a variety of alchemic and runic symbols. See pics below (Also, a close-up of Sirius's Azkaban numbers and info, as someone requested it.).
Here's why I think, though, that this saying -- More or less human -- could be totally valid. I looked up Alchemy on the Wikipedia and found an interesting passage:
Both the transmutation of common metals into gold and the universal panacea symbolized evolution from an imperfect, diseased, corruptible, and ephemeral state toward a perfect, healthy, incorruptible, and everlasting state, so the Philosopher's Stone then represented a mystic key that would make this evolution possible.
In texts that are written according to this view, the cryptic alchemical symbols, diagrams, and textual imagery of late alchemical works typically contain multiple layers of meanings, allegories, and references to other equally cryptic works; and must be laboriously decoded to discover their true meaning.
Wikipedia - Alchemy
While a sentence to Azkaban is certainly not the same as taking the Elixir of Life, if you look sideways and squint hard, you might see a commonality between the goals of the Elixir of Life and a prison sentence. Ostensibly, the man or woman who is sentenced to prison is imperfect and corrupt; the goal is their redemption, to atone for crimes and sin, to make restitution to those harmed (And this doesn't necessary mean an individual; it can refer to a community.). It's about, in theory, seeing a prisoner reach a state of rehabilitation. Rehabilitation is a process, a journey.
The Philosopher's Stone at one time represented a mystic key that unlocked a similar journey, as previously mentioned: the journey from both the transmutation of common metals into gold and the universal panacea symbolized evolution from an imperfect, diseased, corruptible, and ephemeral state toward a perfect, healthy, incorruptible, and everlasting state.
So while an Azkaban prison sentence is about both punishment and breaking a wizard down so thoroughly that he/she may be rehabilitated once he/she has sunk as is as low as humanly possible. Like Fawkes -- all phoenixes, really -- the prisoner has to claw his/her way out of the proverbial as The Philosopher's Stone symbolizes a similar kind of change. This is where I see the connection between alchemic tattoos and, as a prisoner embarks on his/her journey of rehabilitation, there might come a time and a place where that prisoner is "more or less human".
Also, prison tattoos often represent a prisoner's life journey -- they tell life stories. Perhaps the tattoos represent Sirius's story. And prison tattoos are certainly intricate and cryptic, with certain tattoos having very strong and deep meaning.
Finally, I wonder if the source of the saying *More or less human" simply refers to Sirius's status as an Animagus.