I can't seem to change to local date with Custom Javascript "toLocaleDateString"

I'm constructing a form where I'm automating the days and adding extra days from the current day. All seems to be working great. The only issue I run into is that my InDesign is in English, and I would like to keep it that way, but the form is in Dutch. 

Now The current date and time works fine, i changed it to: 

dd MMMM yyyy HH:HH

which outputs as: 17 augustus 2022 11:11

No problem there. I also changed the Dictinoary to Dutch reform 2005. This does seem to change back to English UK Whenever I open and close the file. Might be the issue?

The .js i use is as follows:

#targetengine 'usernameVariable'

function addVariables(openEvent)  

{  

var doc = openEvent.parent;  

while ( doc.constructor.name != "Document" )  

  {  

if ( doc.constructor.name == "Application" ){ return; }  

    doc = doc.parent;  

  }  

// from http://stackoverflow.com/questions/563406/add-days-to-datetime

var today = new Date();  

var tomorrow = new Date(today);  

  tomorrow.setDate(today.getDate()+14);  
    
    const options = {
        year: 'numeric',
        month: 'long',
        day: 'numeric'
    };

  createTextVariable(doc, "Days+14", tomorrow.toLocaleDateString('nl-NL', options));  

}  

function createTextVariable(target, variableName, variableContents)  

{  

var usernameVariable = target.textVariables.itemByName(variableName);  

if (!usernameVariable.isValid)  

  {  

    usernameVariable = target.textVariables.add();  

    usernameVariable.variableType = VariableTypes.CUSTOM_TEXT_TYPE;  

    usernameVariable.name = variableName;  

  }  

  usernameVariable.variableOptions.contents = variableContents;  

}  

app.addEventListener('afterOpen', addVariables);  

which outputs as: Wednesday, August 31 2022

I would like it to output as: 31 augustus 2022 Hence:

    const options = {
        year: 'numeric',
        month: 'long',
        day: 'numeric'
    };

Hopefully some one can help me, thanks in advance.