Don't show superscript ³ with NOT_EXTENDED_ISO10646_1_5X7 (#12513)

Marlin/src/lcd/language/language_en.h

@@ -28,14 +28,20 @@
  * See also http://marlinfw.org/docs/development/lcd_language.html
  *
  */
+#define THIS_LANGUAGES_SPECIAL_SYMBOLS        _UxGT("³")
 
 #define en 1234
 #if LCD_LANGUAGE == en
   #define NOT_EXTENDED_ISO10646_1_5X7
-  #define THIS_LANGUAGES_SPECIAL_SYMBOLS _UxGT("³")
 #endif
 #undef en
 
+#ifdef NOT_EXTENDED_ISO10646_1_5X7
+  #define MSG_CUBED                           _UxGT("^3")
+#else
+  #define MSG_CUBED                           _UxGT("³")
+#endif
+
 #ifndef CHARSIZE
   #define CHARSIZE 1
 #endif
@@ -673,7 +679,7 @@
   #define MSG_FILAMENT                        _UxGT("Filament")
 #endif
 #ifndef MSG_VOLUMETRIC_ENABLED
-  #define MSG_VOLUMETRIC_ENABLED              _UxGT("E in mm³")
+  #define MSG_VOLUMETRIC_ENABLED              _UxGT("E in mm") MSG_CUBED
 #endif
 #ifndef MSG_FILAMENT_DIAM
   #define MSG_FILAMENT_DIAM                   _UxGT("Fil. Dia.")