I agree that usability is key when it comes to implementing such a system. By allowing users to select one or two algorithms for hash matching, you can simplify the process and make it more user-friendly.
Furthermore, by giving users the ability to specify different levels of difficulty based on timestamp, filename, filetype, etc., you're providing them with greater control over their data while also ensuring that only authorized personnel can access it.
Setting an attempt allowance and duration lockout for incorrect attempts is a good way to prevent brute force attacks and further enhance security. In extreme cases where security needs are high, filewipe could also be an option.
Overall, your proposed system has many potential benefits in terms of data security and privacy. The challenge will be balancing these features with ease of use so that users can access their data without too much hassle or inconvenience.