saving and retrieving variables using javascript objects

Discussion & Questions
1

So I'm setting a persistant number variable to a javascript object using a Run Real Javascript action in a After Launching bTT trigger and it seems to save the variable OK but when I try to retrieve it, again in a Run Real Javascript action, this time in a Touch Bar button, I get an undefined result. Is this expected behaviour or am I going to have to encode and decode?

(async ()=> {

	const LrParams = {
		Exposure: "E85E6004-35CF-4BBF-9B0C-283C33ED0555",
		Contrast: "E85E6004-35CF-4BBF-9B0C-283C33ED0555"	
	}

	let result = callBTT('set_persistent_number_variable', {variable_name: 'LrParams', to: 123 })
		.then( (result) =>  {
			returnToBTT(result)
		})
})();

and

(async ()=> {


	let result = await callBTT('get_number_variable', {variable_name: 'LrParams'})
	
	returnToBTT(result)
			
	
})();
2

Interesting; if I use 'get_string_variable' the variable comes back OK, as an object.