Why not have a look at this: Parameterize a Test Object
https://docs.katalon.com/display/KD/Parameterized+a+Test+Object
You will find an example of a Groovy-String as XPath with a ‘index’ variable.
"//*[@id="main"]/div/table/tbody/tr[2]/td[${index}]/input"
And you can give value to the index variable with 2nd Map argument to findTestObject method call.
WebUI.check(findTestObject('chk_Title', [('index') : it]))