Former (many years ago) wxHaskell maintainer here.
There is more technical work involved in maintaining wxHaskell than you might think, and much of it is pretty thankless, especially if your interest is Haskell.
There are several parts that make up wxHaskell:

    A C language binding over wxWidgets (which is C++). Some of this is auto-generated, but some parts are implemented manually.

    A rather complex build system - complex because it is auto generating then building the C binding and linking with the FFI.

    A low level API in Haskell which is basically a Haskell representation of the C language bindings

    The high level binding on top of the low level binding which is what you actually want to use.

Putting this all together, most of the work is in C, a little Haskell FFI and far more build system work than any sane human would ever take on voluntarily.
The thing that really put me off of maintaining (I stuck with it for about five years) was the fact that virtually every new release of GHC or Cabal would break things in fairly simple ways requiring tedious debug and fix - it was all really a waste of time.
In the end it was the lack of any meaningful policy on backward compatibility that drove me away from Haskell, but I wish anyone wanting to take on the type of work above the very best of luck.