Lovage: Easy to get hold of if you're in Europe according to Wikipedia "its flavor and smell can be described as a mix of Celery and Parsley, but with a higher intensity of both of those flavors". So, literally just add in a large amount of those to compensate for the strength.
Caroneum: According to this website[0] "as long as you can find a carton of white grape juice, you're set" to make it, so that's readily available.
Rue - According to Wikipedia "Rue extracts are mutagenic and hepatotoxic". It's bitter, so you could very likely substitute a fair amount of Fenugreek for it, which is bitter but fragrant.
Laser Root - Also known as Ailphium, this no longer exists. However, Asafeotida "had similar enough qualities that Romans, including the geographer Strabo, used the same word to describe both". So literally just use that.
So in other words you use Pepper, Cumin, Coriander, Celery, Parsley, Homemade Caroneum, Fenugreek, Asafeotida, and Honey.
Which really doesn't sound that difficult to get hold of, does it?
[0]: https://pass-the-garum.blogspot.com/2013/03/caroenum.html