Activate Transaction Splitter using a macro button?

Is there any way to add a small button object on the transactions page that can be clicked to automatically bring up the splitter window?

I recorded a macro but it stalls at the showSplitter() function (see below). There should be some way to reference a call to the extension code but I cannot figure it out. Any help?

function SplitCat() {
var spreadsheet = SpreadsheetApp.getActive();
spreadsheet.getRange(‘D9’).activate();
showSplitter();
};