I've noticed several more issues with the kawa.jar that I produced by
manually changing gnu/expr/Mangle.java:
when I try to run the terminal version of GRASP, I get a bunch of warnings
like:

"no declaration seen for shift-left"
"no declaration seen for shift-top"

etc.

Those identifiers are names of fields in a superclass. The superclass in
this case is CharPainter:
https://github.com/panicz/grasp-android/blob/master/stages/retreat/GRASP/src/text-painter.scm#L16

I use a "define-object" macro which - rather trivially - expands to
"define-class":
https://github.com/panicz/grasp-android/blob/master/stages/retreat/GRASP/src/define-object.scm

(define-object (ClassName constructor-args ...)::Interface
  (define name :: type value)
  (define (method args ...) ...)
  (SuperClass super-constructor-args ...)
  init-code ...)

expands to something like

(define-class ClassName (Interface SuperClass)
  (name :: type init: value)
  ((method args ...) ...)
  ((*init* constructor-args ...)
   (invoke-special SuperClass (this) '*init super-constructor-args ...)
   init-code ...))

(and it certainly worked with the previous kawa.jar)

Anyway, it seems that the code of the subclass is unable to see the slots
defined in its parent class.
I suspect that this might have something to do with mangling/unmangling.

I will try to verify this tomorrow by replacing the identifiers like
shift-left with something more like shiftLeft
to see if that helps.