Hey, your new friend in HERRIMAN, here.

Wonder if you have ideas on how to best nurture these seedlings. My "expert" Utah plant group really gave no information.

to NGA
Lucky you! Artemisias slow their grow in late summer, the seedlings could be doing what the adult plants do, preparing for winter dormancy. I'd leave them in the soil and transplant when they emerge in spring. This species is hardy to z4 possibly 3 depending on sources. As you've probably observed, most artemisias are tough unless over watered or babied with rich soil. Strong scent —I'd be surprised if deer like them.
What is your hardiness zone? The parent plant is apparently hardy in your area. You could protect the seedlings in situ if you get colder than usual.

I would wait until spring to transplant, too. You will want to mark them in the landscape so you can find them later.

Sorry for the late reply and hello from next door in South Jordan! As the others have suggested, waiting till Spring is best. You might also want to try dividing some of the bigger pre-existing plants on your property. If you go that route, late Fall after the plant is dormant is probably the best time.
A side note: for fun, you could try testing the fragrance on the different plants as the smell can differ slightly. I once found a wild plant that smelled like bubblegum!

Wow! Finding a sweet smell with any Artemisia is quite a fluke, and well worth introducing into the horticultural trade. A. ludoviciana, although great in wild settings, isn't a particular draw for gardens, but a "bubblegum" odor could be a hybridizer's dream gene to mix with other Artemisia species. Many people don't care fore the normal Artemisia smell.

40 years ago, I found a mutant hosta with a decidedly yellow flower. Hostas don't interest me, especially back then, but I've been kicking myself ever since for not propagating it.

Here is A. ludoviciana ssp. ludoviciana in a Minnesota sand prairie.

I wonder if Ângelo stumbled upon one of the Texas Rangers, Leucophyllum pruinosum, aka Bubblegum Bush. A lovely xeric shrub with grey-green leaves, similar to the better known L. frutescens, but instead of that typical camphorous scent, grape bubblegum!

I wish we had wild Leucophyllum here! If we did I would definitely have some in my yard.
Unfortunately the closest place to the Salt Lake Valley that I've seen them for sale is St. George in the very far southwestern corner of the state.