Thanks for that list, I know that the first four are regularly associated with Gruit. I did some
brief research into all of the ones you listed and included what I found bellow.
On the issue of Yarrow, that's actually one of the more benign of the traditional herbs used in Gruit: it's known to be an allergen (similar to ragweed, chrysanthemums, marigolds, daisies, and similar plants), It should not be used by pregnant/breastfeeding women, may impede clotting (much like alchohol) and should not be taken or used within 2 weeks of surgery. Unlike several of the other herbs used in traditional gruit, it has no Narcotic or Psychoactive properties.
Juniper - Not an acceptable substitute (yes a traditional herb used in Gruit, for flavor), no antimicrobial/antiseptic properties. Also, several of the members of my local homebrew club are severely allergic (including my wife) so I won't be using it at all.
Bog Myrtle (Sweet Gale) - One of the big 3 in Gruit, also lacks antimicrobial/antiseptic properties, it's main use was because it's nuts are psychoactive. I will be using a little in one of my Gruits.
Caraway - No antimicrobial/antiseptic properties, mainly used for flavor
Mugwort - No antimicrobial/antiseptic properties, some parts are used in herbal teas as a stimulant/diuretic, used in beer for flavor (bittersweet) and clarification.
Grape Seeds - No antimicrobial/antiseptic properties, way to expensive to use in my beer.
Rosemary -
May have antimicrobial/antiseptic properties will look into it further, the seeds were used in gruits, and have narcotic properties. May lead to worse hangovers
Cloves -
Proven antimicrobial/antiseptic properties will look into how much would be needed and in what ways to use it. The flavor of cloves can be overwhelming, if it's not the primarily desired flavor it will be difficult to overcome.
Cardamom -
May have antimicrobial/antiseptic properties will look into it further. The flavor would probably be good for sweet beers.
Laurel - No antimicrobial/antiseptic properties, probably good for aromatic uses in beer though.