Speaking from experience, I guarantee you that anyone who starts saying "centis" instead of "percent equals," whether in the context of Hoon or Haskell lenses or anything, will never go back. I have to force myself to "code-switch" when speaking to the uninitiated, even in a technical context that has nothing to do with Urbit. And I'm not the only one.
I can't fault Haskellers for their daring in pushing the limits of programming languages as a UI. For instance, the idea of custom, library-specific "line noise" terrifies me. Hoon has no macros, no custom syntax, no operator overloading, etc. Once you've learned the line noise you've learned it.
The lens library in particular is a DSL by anyone's definition. Arguably (well, I'd argue it anyway), the ease of constructing DSLs is a trap that's impeded adoption of both major families of FP, Lisp and Haskell/ML. Plenty of people have made the "DSL == write-only" argument, so hopefully it's sufficient to just reference it.
Lens is in a sense the quintessential expression of Haskell; I don't know how anyone grounded in reality could expect the average Java programmer to learn and master it. And yet, everything it's doing is beautiful and true and right. Basically, resolving this contradiction strikes me as the essential problem of functional programming, if not just programming, in the next decade. I personally am very far from being the most qualified person to solve this problem. But I feel not enough people are working on it.