It doesn't matter that the keys are in HEX. You can convert them to WIF and then use the according base keys to generate valid address. I encountered the same problem. WIF validation may be correct however there are way too many possible keys. What is interesting is uncompressed format there is a few less bytes to deal with, which in turn could be converted back to compressed if needed. Ill leave a couple examples here.
EC 0000000000000000000000000000000000000000000000000000000000000001
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf
EC 0000000000000000000000000000000000000000000000000000000000000003
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74sHUHy8S
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreB1FQ8BZ
EC 00000000000000000000000000000000000000000000000000000022382FACD0
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9P3MahktLW5315v
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB4BW8dsj4c9a6g
EC 000000000000000000000000000000000000000000000001A838B13505B26867 - puzzle 65
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qZM21gaY8WN2CdwnTG57
5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ipCnYRNeQuRFKarWVVs
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74sHUHy8S
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9P3MahktLW5315v
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qZM21gaY8WN2CdwnTG57
So we could say upcoming puzzles private key 66 will start with...
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3