come on…

when U add a line, you have a trailing comma

activeLow : false, 

right?

activeLow = false,

not =

activeLow : false

{
		    	module: 'MMM-Buttons',
			//position: "middle_center",
		    	config: {
				buttons: [
			    	{
					pin: 5,
					activeLow = false,
					name: "test_button",
					longPress: {
					notification: "PAUSE_STOPWATCHTIMER",
				    	payload: {action: "PAUSE_STOPWATCHTIMER"}
				},
					shortPress: {
				    	notification: "START_STOPWATCH",
				    	payload: {action: "START_STOPWATCH"}
					}
			    	}
				]
		    	}
		}
and I get this error: 

[ERROR] WARNING! Could not validate config file. Starting with default configuration. Please correct syntax errors at or above this line: /home/group6/MagicMirror/config/config.js:117
activeLow = false,
^^^^^^^^^^^^^^^^^

SyntaxError: Invalid shorthand property initializer
at internalCompileFunction (node:internal/vm:73:18)
at wrapSafe (node:internal/modules/cjs/loader:1160:20)
at Module._compile (node:internal/modules/cjs/loader:1212:27)
at Module._extensions…js (node:internal/modules/cjs/loader:1311:10)
at Module.load (node:internal/modules/cjs/loader:1098:32)
at Module._load (node:internal/modules/cjs/loader:945:12)
at c._load (node:electron/js2c/node_init:2:13672)
at Module.require (node:internal/modules/cjs/loader:1122:19)
at require (node:internal/modules/helpers:130:18)
at loadConfig (/home/group6/MagicMirror/js/app.js:117:14)
at App.start (/home/group6/MagicMirror/js/app.js:250:18)
at Object. (/home/group6/MagicMirror/js/electron.js:193:7)
at Module._compile (node:internal/modules/cjs/loader:1256:14)
at Module._extensions…js (node:internal/modules/cjs/loader:1311:10)
at Module.load (node:internal/modules/cjs/loader:1098:32)
at Module._load (node:internal/modules/cjs/loader:945:12)

``t

activeLow

can you add this to your button definitions

after pin:
activeLow: true or false depending on how you have it wired
if the signal is high when pressed, then false.
if it has a pull up resistor then true, it will be pulled down when pressed

you said your python is reporting high sll the time