Meanwhile, seeds with approximately 16-18 words are very difficult if the sequence is missing or there are 2 words missing. and cases like this have a nearly 20% chance of success.
I was one of the people who lost 0.003 bitcoins because of it. and decided to take off the blockchain account for a moment ..
I think this is mostly because their seed mnemonics could be anything from 15 to 21 words and their wordlist was really weird almost 50000 words.
We have backward engineered their source code from 2013/14 (now removed from their github but we found an internet archive partial snapshot) and are able to find the mnemonic seed even with 2-3 words wrong or missing
/KX