You can't localize keyEquivalent. As you said the value may change depending on the active keyboard layout. The one approach is to use virtual keycode (position of the key on keyboard). Use this virtual keycode to translate it to string.
Recipe here: Convert key code into key equivalent string
From MASShortcut.framework documentation:
For example for the ^2 keyboard shortcut
(kVK_ANSI_2+NSControlKeyMask to be precise) the keyCodeString is
2 on the US keyboard, but ě when the Czech keyboard layout is
active. See the spec for details.
From Events.h
/*
* Summary:
* Virtual keycodes
*
* Discussion:
* These constants are the virtual keycodes defined originally in
* Inside Mac Volume V, pg. V-191. They identify physical keys on a
* keyboard. Those constants with "ANSI" in the name are labeled
* according to the key position on an ANSI-standard US keyboard.
* For example, kVK_ANSI_A indicates the virtual keycode for the key
* with the letter 'A' in the US keyboard layout. Other keyboard
* layouts may have the 'A' key label on a different physical key;
* in this case, pressing 'A' will generate a different virtual
* keycode.
*/
enum {
kVK_ANSI_A = 0x00,
kVK_ANSI_S = 0x01,
kVK_ANSI_D = 0x02,
kVK_ANSI_F = 0x03,
kVK_ANSI_H = 0x04,
kVK_ANSI_G = 0x05,
kVK_ANSI_Z = 0x06,
kVK_ANSI_X = 0x07,
kVK_ANSI_C = 0x08,
kVK_ANSI_V = 0x09,
kVK_ANSI_B = 0x0B,
kVK_ANSI_Q = 0x0C,
kVK_ANSI_W = 0x0D,
kVK_ANSI_E = 0x0E,
kVK_ANSI_R = 0x0F,
kVK_ANSI_Y = 0x10,
kVK_ANSI_T = 0x11,
kVK_ANSI_1 = 0x12,
kVK_ANSI_2 = 0x13,
kVK_ANSI_3 = 0x14,
kVK_ANSI_4 = 0x15,
kVK_ANSI_6 = 0x16,
kVK_ANSI_5 = 0x17,
kVK_ANSI_Equal = 0x18,
kVK_ANSI_9 = 0x19,
kVK_ANSI_7 = 0x1A,
kVK_ANSI_Minus = 0x1B,
kVK_ANSI_8 = 0x1C,
kVK_ANSI_0 = 0x1D,
kVK_ANSI_RightBracket = 0x1E,
kVK_ANSI_O = 0x1F,
kVK_ANSI_U = 0x20,
kVK_ANSI_LeftBracket = 0x21,
kVK_ANSI_I = 0x22,
kVK_ANSI_P = 0x23,
kVK_ANSI_L = 0x25,
kVK_ANSI_J = 0x26,
kVK_ANSI_Quote = 0x27,
kVK_ANSI_K = 0x28,
kVK_ANSI_Semicolon = 0x29,
kVK_ANSI_Backslash = 0x2A,
kVK_ANSI_Comma = 0x2B,
kVK_ANSI_Slash = 0x2C,
kVK_ANSI_N = 0x2D,
kVK_ANSI_M = 0x2E,
kVK_ANSI_Period = 0x2F,
kVK_ANSI_Grave = 0x32,
kVK_ANSI_KeypadDecimal = 0x41,
kVK_ANSI_KeypadMultiply = 0x43,
kVK_ANSI_KeypadPlus = 0x45,
kVK_ANSI_KeypadClear = 0x47,
kVK_ANSI_KeypadDivide = 0x4B,
kVK_ANSI_KeypadEnter = 0x4C,
kVK_ANSI_KeypadMinus = 0x4E,
kVK_ANSI_KeypadEquals = 0x51,
kVK_ANSI_Keypad0 = 0x52,
kVK_ANSI_Keypad1 = 0x53,
kVK_ANSI_Keypad2 = 0x54,
kVK_ANSI_Keypad3 = 0x55,
kVK_ANSI_Keypad4 = 0x56,
kVK_ANSI_Keypad5 = 0x57,
kVK_ANSI_Keypad6 = 0x58,
kVK_ANSI_Keypad7 = 0x59,
kVK_ANSI_Keypad8 = 0x5B,
kVK_ANSI_Keypad9 = 0x5C
};
/* keycodes for keys that are independent of keyboard layout*/
enum {
kVK_Return = 0x24,
kVK_Tab = 0x30,
kVK_Space = 0x31,
kVK_Delete = 0x33,
kVK_Escape = 0x35,
kVK_Command = 0x37,
kVK_Shift = 0x38,
kVK_CapsLock = 0x39,
kVK_Option = 0x3A,
kVK_Control = 0x3B,
kVK_RightCommand = 0x36,
kVK_RightShift = 0x3C,
kVK_RightOption = 0x3D,
kVK_RightControl = 0x3E,
kVK_Function = 0x3F,
kVK_F17 = 0x40,
kVK_VolumeUp = 0x48,
kVK_VolumeDown = 0x49,
kVK_Mute = 0x4A,
kVK_F18 = 0x4F,
kVK_F19 = 0x50,
kVK_F20 = 0x5A,
kVK_F5 = 0x60,
kVK_F6 = 0x61,
kVK_F7 = 0x62,
kVK_F3 = 0x63,
kVK_F8 = 0x64,
kVK_F9 = 0x65,
kVK_F11 = 0x67,
kVK_F13 = 0x69,
kVK_F16 = 0x6A,
kVK_F14 = 0x6B,
kVK_F10 = 0x6D,
kVK_F12 = 0x6F,
kVK_F15 = 0x71,
kVK_Help = 0x72,
kVK_Home = 0x73,
kVK_PageUp = 0x74,
kVK_ForwardDelete = 0x75,
kVK_F4 = 0x76,
kVK_End = 0x77,
kVK_F2 = 0x78,
kVK_PageDown = 0x79,
kVK_F1 = 0x7A,
kVK_LeftArrow = 0x7B,
kVK_RightArrow = 0x7C,
kVK_DownArrow = 0x7D,
kVK_UpArrow = 0x7E
};
