AutoHotKey v2.0.2: How to trigger HotKey on square bracket - autohotkey

Question

I am trying to remap the opening square bracket ([) to a lower case u-umlaut (ü) and the opening curly bracket ({ / Shift+[) to the upper case U-umlaut (Ü) on a US keyboard layout using a AutoHotkey script.
The following works very well with ; to ö and : to Ö but the Variantes for ü and Ü don't. I suspect it's because a square bracket has a special meaning but there is no error about Syntax and AutoHotkey's escape Syntax with ` does not apply here.
I believe that the problem is the trigger $[:: because the first block with KeyWait alone without the second Up part does not prevent me typing [ while it does when I try that with ;.
Please explain what I am doing wrong.
#Requires AutoHotkey v2.0
#SingleInstance Force
LongPressDelay := 220
; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; O-Umlaut | ; => ö und : => Ö
$;::
{
KeyWait ";"
return
}
$; Up::
{
If (A_PriorHotKey = "$;" AND A_TimeSincePriorHotkey < LongPressDelay)
Send ";"
else
Send "ö"
return
}
$+;::
{
KeyWait ";"
return
}
$+; Up::
{
If (A_PriorHotKey = "$+;" AND A_TimeSincePriorHotkey < LongPressDelay)
Send ":"
else
Send "Ö"
return
}
; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; U-Umlaut| [ => ü und { => Ü
$[::
{
KeyWait "["
return
}
$[ Up::
{
If (A_PriorHotKey = "$[" AND A_TimeSincePriorHotkey < LongPressDelay)
Send "["
else
Send "ü"
return
}
$+[::
{
KeyWait "["
return
}
$+[ Up::
{
If (A_PriorHotKey = "$+[" AND A_TimeSincePriorHotkey < LongPressDelay)
Send "{"
else
Send "Ü"
return
}
; EDIT: My working solution per user3419297's answer
; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; U-Umlaut| [ => ü und { => Ü
$SC01A::
{
KeyWait "SC01A"
return
}
$SC01A Up::
{
If (A_PriorHotKey = "$SC01A" AND A_TimeSincePriorHotkey < LongPressDelay)
Send "["
else
Send "ü"
return
}
$+SC01A::
{
KeyWait "SC01A"
return
}
$+SC01A Up::
{
If (A_PriorHotKey = "$+SC01A" AND A_TimeSincePriorHotkey < LongPressDelay)
SendText "{"
else
Send "Ü"
return
}
Script based on https://www.autohotkey.com/board/topic/80697-long-keypress-hotkeys-wo-modifiers/?p=689354
Context:
As a Developer it's super helpful to code using the US keyboard layout because all the special characters are within easy reach. As a native German speaker I'd like to access our beloved Umlauts at their traditional spots because I'm used to it.
On MacOS I solved this with Karabiner and Umlauts on long press. I want to replicate this on Windows.

Answer 1

In the rare case where a key has no name or the standard code doesn't work, Hotkeys can be triggered by using the 3-digit hexadecimal scan code (SC) of a key.
The scan code of a key can be determined by following the steps at Special Keys:
Run a script with keyboard hook
open the AutoHotkey window (context menu in systray, Open item)
go to View > Key History and script info
type the key
hit F5 to see the code

Answer 2

Trying the same right here, using a different code though.
https://www.autohotkey.com/boards/viewtopic.php?f=9&t=99809
I managed to migrate it to V2 and changed the keys to match the German Keyboard layout.
[ = ü
' = ä
; = ö
- = ß
Please feel free to try:
$[::
$+[::
$'::
$+'::
$;::
$+;::
$-::
{
umlaut_pairs := Map("$[" , "ü", "$'" , "ä", "$;" , "ö", "$-" , "ß", "$+[" , "Ü", "$+'" , "Ä", "$+;" , "Ö")
umlaut := umlaut_pairs[A_ThisHotkey]
Send SubStr(A_ThisHotkey,2) ; input the letter first, otherwise input order might be wrong
KeyWait Substr(A_ThisHotkey,-1), "T0.2" ; call only the specific character without "$" or "+" and show input of the pressed key
if(A_TimeSinceThisHotkey>200) ; if pressed more than 200ms
{
Send "{BackSpace}" ; backspace previous letter
Send umlaut_pairs[A_ThisHotkey] ; Replace acc. to the map
KeyWait Substr(A_ThisHotkey,-1), "T0.2"
; }
}
}