If you drop the grammar requirement, you can easily use one of the many dictionaries made for this purpose (e.g. diceware or a bip39 wordlist which even has sup

If you drop the grammar requirement, you can easily use one of the many dictionaries made for this purpose (e.g. diceware or a bip39 wordlist which even has support for many languages). If you feel fancy, you could make it order independent or add error correcting codes to compensate for a limited number of mistakes at the cost of an extra word or two.