You can follow almost every metric and dimensions from Facebook Ads, but you need to follow one rule to make it work:
Values in the query need to follow Facebook API documentation. You can most of the supported metrics and dimensions here.
Now, let's get to adjusting the template.
Browse this list of metrics and find the column you would like to export. Let's say you are interested in following frequency. The API call to download the metric is, simply enough, "frequency".
Go to your connector and enable the Advanced Editor. Then find the parameters section in the query.
Add the frequency metric.
The last step is to add it to the dataset as a metric. It is very important as to call a parameter without a definition assigned to it, can lead to an error. To do this, add the new metric to the "transform list".
The Code defines the name of the column.
The Source parameter is referring to the source parameter above the transform parameter. JSON will go and check if there is the same source(in this instance "frequency") and if it is, it will populate the column with those data.
After that, you are ready to save the adjustment and test it in the preview. In your newly customised template the results in your Excel sheet should look like this.