Use this to swap Left and Ctrl and have Ctrl + Tab working as Alt+tab

mac_final.ahk

#MaxThreadsPerHotkey 3
SetBatchLines, -1

; Swap LeftCtrl and LeftAlt while maintaining Alt+Tab behavior
*LCtrl::
  CtrlTabbed := false
  Hotkey, *Tab, CtrlTab, On ; Enable Ctrl+Tab handling
  Send {Alt Down} ; Press Alt (LCtrl::Alt)
  KeyWait, LCtrl
  if CtrlTabbed
    Send {Ctrl Up} ; Release Ctrl after Ctrl+Tabbing
  else
    Send {Alt Up} ; Release Alt (LCtrl::Alt)
  Hotkey, *Tab, CtrlTab, Off ; Disable Ctrl+Tab handling
  CtrlTabbed := false
return

CtrlTab:
  if (!CtrlTabbed) {
    Send {Alt Up} ; Release Alt now
    Send {Ctrl Down} ; Press down Ctrl
    CtrlTabbed := true ; Set a flag so we know to release Ctrl instead of Alt
  }
  Send {Blind}{Tab} ; Press Tab without releasing any modifiers
  ; No need to release Ctrl here because it will be released when LCtrl is released
return

; Swap LeftAlt and LeftCtrl while maintaining Alt+Tab behavior
*LAlt::
  AltTabbed := false
  Hotkey, *Tab, AltTab, On ; Enable Alt+Tab handling
  Send {Ctrl Down} ; Press Ctrl (LAlt::Ctrl)
  KeyWait, LAlt
  if AltTabbed
    Send {Alt Up} ; Release Alt after Alt+Tabbing
  else
    Send {Ctrl Up} ; Release Ctrl (LAlt::Ctrl)
  Hotkey, *Tab, AltTab, Off ; Disable Alt+Tab handling
  AltTabbed := false
return

AltTab:
  if (!AltTabbed) {
    Send {Ctrl Up} ; Release Ctrl now
    Send {Alt Down} ; Press down Alt (Keeps the Alt+Tab menu open)
    AltTabbed := true ; Set a flag so we know to release Alt instead of Ctrl
  }
  Send {Blind}{Tab} ; Press Tab without releasing any modifiers
  ; No need to release Alt here because it will be released when LAlt is released
return

; Handle Right Alt separately
RAlt::
  Send {RAlt Down}
  KeyWait, RAlt
  Send {RAlt Up}
return

Return