You can't interact with a table using push. You need to set the data source. You can use a "variable" that is an array (used to be called "temporary state").
You don't use push there either. You need to use items.setIn or items.setValue
couple more things
I didn't see any mutations of the input data in your transformer. If you put the components in a form you can just use form1.data to get an object. Then you don't need the transformer
you can use push on an arrays you define in a js query; let arr = [];
No problem. One more thing I like to enable in js query when using setValue or setIn (I'm not 100% sure setIn is impacted like setValue; seems like it)... is "Keep variable references inside the query in sync with your app". Note this may cause performance issues depending on your app.