As I read the OP the question that popped up in my mind is:  If I were to have my cold wallet stolen, or if I were to steal one, what is the possibility of selecting seed words at random and gaining access.  I also presume that the seed is not global, but local to each wallet and to each account on the wallet.  A search stated that there are 2048 seeds in the library.

I entered some numbers in an Excel work book for this.  With a library of 2048 seeds, presuming repeats are not allowed, the probably of getting the first one right is 1/2048.  For the second one, divide by 2047, then by 2046, etc.  By the time we get to the

11th word:  1 out of 2.58789 * 10^^36
23rd word: 1 out of 1.27862* 10^^76

That is about the size of the private key.

I suspect that after some number of tries each cold wallet will do something like: 
A) delete its private key(s).  Not the best, but at least the thief is not rewarded. 
B)  each time a bad sequence is provided slow down the response.  Start with, maybe 1 second of additional time, then double the time for each attempt.  It could write the number of attempts into a storage location and reset it upon getting the correct seed.

When I did a seed check with my wallet, there are a few seconds delay before it was ready for the next word.  That would introduce sufficient time to deter any thief.
Is this reasonable?  Or do I have a flaw in my understanding?