If you’re speaking in general, it’s best to use present simple. However, if you’re talking about a specific case, I would use past simple: The people who wrote these reviews might never have imagined that the author would read them.

Teacher Trevin gave an excellent answer.

I think there are multiple possibilities with nuanced meanings. The exact context around this sentence would give more clues as to which tenses to choose. People who write reviews may never imagine the authors themselves will read them. (general and hypothetical) People who had written reviews may never have imagined the authors themselves would have read them. (Reviews were actually written by people and *probably* read by the authors. The use of the past perfect in the first clause underlines the sequence of events and emphasizes that the actions of the review writers took place first.) Also note that in your second example: "The people who have wrote reviews may never imagine the authors themselves will read them" there is an error in your formation of the present perfect. The past participle of "write" is "written" so you could say "People who have written reviews might never have imagined the authors themselves would read them." (This option is more ambiguous than the previous one. It is a general statement and doesn't necessarily mean that the authors actually read the reviews, just that the writers of the review didn't expect the authors to read them.) This is a complex question with multiple possible answers. If you would like to learn more about past tenses and modal verbs, book a lesson with me. I have some lesson materials that could help you. Have a great one!