I think the article linked explains how to do TripleWhale connection with specific platforms not-including Funnelish for some reason.
Perhaps reach out to TripleWhale support they might have up to date instructions on how to do it with alternative platforms such as Funnelish as I have no idea how to adapt their instructions to our platform.
If you can get someone from TripleWhale team to collaborate on here I can aid them if needed to adapt the code to your checkout or Funnelish in general.