Small correction - not that is makes things work:
^[⌃⇧⌥⌘]{1,4}\s\w
The first character is the caret (Shift+6) and is the regex start of string character. The second instance is a different, symbol character Unicode #2303, the “UP ARROWHEAD”.
I’d not try to fix this for now until we have a steer as to how Tinderbox’s regex engine is handling these unicode symbol characters.