The Action Text column won’t show if there is no value.
Also, if you can’t edit anything, that means that your screen isn’t attached to a row…meaning that you either don’t have any rows in the table, or you have a filter on the screen that filtered out any valid rows. In my example, I have a single row, so the screen can attach to that row and my entry components will update those columns in real time. That’s why I have the one row with an ‘x’ in my example. That was just to generate a row so that I can edit it with the entry components.
The rest should just work since you aren’t using a form. The math and template column will dynamically update as you enter values. Once you have everything entered as you like, then the button will perform an Add Row action which will take all of those entered values and the calculated result and you can write them to a log sheet.
I’d also like to mention that the columns that you fill with the entry components should ideally be User Specific columns. That way multiple people can use the app and update the values without interfering with any other user that may be using the app at the same time.