In Spanish (es_ES), French (fr_FR), and Swedish (sv_SE), the shortcut Shift + S is assigned to both Before Only and Destination Gamut Warning (in Soft Proofing). Typing Shift + S always invokes Before Only.
The relevant TranslatedStrings lines:
"$$$/AgDevelop/Menu/View/BeforeAfter/Before/Key=Shift+s"
"$$$/AgDevelop/Menu/View/OutputGamutWarning/Key=Shift+s"
All languages assign Shift + S to Destination Gamut Warning.