So this template renders xlsx?
const appendRes = await jsreport.render({ template: { shortid: 'Cvw4vfrtg'} });And you want to run the unoconv to convert it to the pdf? Why don't you define the unoconv pdf conversion directly on the template properties?
If you need to configure unoconv dynamically, you can do it just like any other prop
const appendRes = await jsreport.render({ template: { shortid: 'Cvw4vfrtg', unoconv: { format: "pdf", enabled: true } } });