There is an Imam in my area who was asked about an ayah which talks about the hands of Allah and he said “this is a disgusting way to translate it”. Would our prayers behind him be valid? Also I’ve known of this but still prayed behind him since I couldn’t takfir him myself. Was this correct?

Yes, because he might have fallen into this out of Ta'wil, just like many people have fallen into it. Praying behind somebody who has fallen into an innovation within religion is correct and allowed, because his prayer is correct for himself. The rule is, as the Imams have said: whosoever's Salah is correct for him, then it is correct for those who pray behind him.