Hey @julescolle – if I am heading down the right path for you, you merely want to set default values for fields (if no value is entered yet)?
One way is that you can set default values right from the get_field() without any conditional logic snippets.
$example = get_field( 'cpar_example' ) ?: 'use this value if not entered';
This would then display block preview with those default values when first added to the editor and/or preview. Then when entering a value into the fields, it would override.
Hope this helps…