I don't know. Let's try it.

src/4cade.init.a

@@ -43,6 +43,8 @@
          sec
          jsr   $FE1F                 ; check for IIgs (allows super hi-res artwork)
          bcs   @NotGS
+         lda   #$40                  ; enable auxmem-to-bank-E1 shadowing on IIgs
+         sta   SHADOW
          sec
          +HIDE_NEXT_BYTE
 @NotGS   clc

src/ui.attract.shr.a

@@ -128,9 +128,6 @@ BlankSHR
 
          sta   WRITEAUXMEM           ; writes go to auxmem
 
-         lda   #$00                  ; enable auxmem-to-bank-E1 shadowing on IIgs
-         sta   SHADOW
-
          lda   #$20                  ; clear $2000..$9FFF in auxmem
          ldx   #$80
          jsr   ClearMem