What else is in the terrarium?
did you plant the seeds in one general area?
If the area you planted is generally free of other plants, and if you know the general area they are planted..I would try this..
scoop out all the media in that area containing the seeds, throw it all into a big bucket of water..and try to separate the media from the seeds...
if its peat, you can make a big sludge milkshake out of the peat, dilute it with a lot of water..(im thinking a fist-full of peat in a 5-gallon bucket of water)..strain it through some fine mesh, and you might be able to recover the VFT seeds..
If its spagnum, the seeds might also separate from the media..seeds will either sink or float..either way you might be able to separate them from the media..
sundew seeds might not work so well, because they are usually REALLY tiny..
what kind of sundew seeds are they?
IMO thats your best bet..try to separate the seeds from the media and re-sow..
yes, 1" deep is too deep..
as a general rule of thumb, any seed, regardless of the plant, shouldnt be planted to a depth that is more than twice the diameter of the seed..the smaller the seed, the shallower the depth..something like a sunflower or pumpkin seed can go 1" deep..
and BTW, growing CPs from seed is way overrated..its not really worth the effort IMO..
(it takes 5 years to get an full-size VFT from seed..and nearly all will die before they make it that far)
its much easier to just buy mature plants.
Scot