Nearly fifty years old, born in the UK, living in N.Italy for too many years, but a frequent visitor to the UK and Ireland: can't say I have never seen ‘mensch’ online, or that my mind exploded when I read the OP's sentence. By the way should it be written with a capital letter?
In its proper context the meaning of ‘mensch’ was easy enough to guess. But I'm used to guessing meanings, living in Italy there are so many different dialects, you have no choice but to develop a sense of intuition. I think this is a common characteristic among speakers of more than one or two languages.
However, if knowing its precise meaning of was of real importance, it's easy enough to look it up online. I would not recommend using this term in speech in the UK, unless you were sure your audience was familiar with the expression, (this holds true for the US as well), but it might be a handy trick in a presentation which is lagging pace; a humorous side-note added by the OP: "for the gentiles in the audience, ‘mencsh’ is Yiddish for a person of honour", said with a smile and a wink, it would be memorable.