I haven't tried that particular eryngium, but according to the Clothiers database they are slow to germinate and not all seedlings will appear at the same time. In my own Z8, putting the pots outdoors from about Nov into early March would make them independent of me having to watch them closely but there is very little chance of any pot drying out here over late Fall and Winter. My winter temps will often be a day/night average of 40F

Clothiers - Eryngium campestre , Sow at Max. 5ºC (41ºF), germination irregular, often several months

Hi Savannaht. I haven't tried campestre species in particular.
But with E. alpinum & giganteum cultivars, I have figured out that (unless seeds are not viable to begin with), if they aren't sown almost directly from the the bract, in which case some can germinate within weeks, they can otherwise be rather more difficult/slower, unless the outer seed coat is removed first.

Try using a new damp coffee filter in a plastic baggy, if you aren't already. Carefully use your fingernails to gently remove the outer seed coat & once hulled, quickly place each on the moist filter, as it is important to avoid allowing it to dry out.
The inner seed coat will appear much like a sunflower seed.
Expose these seeds to afternoon or morning light, indoors in a windowsill, but be sure it doesn't make them get too warm.
Then place back in the refrigerator, as the seeds should have started to swell & may turn pale green.
I've noticed they can actually rot more easily, if they aren't cooled down, while in the process of producing a root.
But, since you've pre-stratified them they may just germinate with ease, once the seed coat has been removed without requiring any more cooling & without rotting.
You'll have to keep watch...
If they don't start to germinate &/or rotting starts to occur- Chill again & be patient.
Once the rootlet appears you can pot those up & they should do fine with afternoon shade. After several true leaves have grown, you may carefully plant them out, while trying not to disturb the tap root too much, in the process.
hth