The problem is that all of your path statements try to access an element in an array. E.g. the [1] in:
JSONPATH:$.result.watt_hours_day.[1]
But there is no array in your JSON. This is an unfortunate side-effect of how forecast solar formats their return data. Each set of data is not an array of timestamps and values but an object where the timestamps are the keys. So you would have to use something like:
JSONPATH:$.result.watt_hours_day.2022-11-03
Of course, this is not going to work for a configuration in the JSONPATH because tomorrow the key will be different and you can’t (to my knowledge) put a dynamic value in the JSONPATH transformation.
There are a couple of possible solutions here:
The easiest solution is probably to just keep the entire return JSON in a single string item and then use a rule when that string changes to parse that item according to the current date and populate the other items you want.
You could also use a JS transform instead of a JSONPATH transform and write a JS script that will parse the item item and return the value you want. Of course, if you want more than one value, you’ll need a different JS transform script for each channel.
Instead of doing this yourself you could look at the Solar Forecast PV add-on that handles Forecast Solar as one of its options: