I'm a security professional and this looks like a great tool for OP's use case, especially with strong passwords and great password hints. I think your secrets are well stored - unless your mother stores the password to these files insecurely, a problem that is not new to this solution.
This also applies to most if not all challenges mentioned by other posters. Take phishing for example, at the moment all methods to exchange information of interest that are at the same time user friendly are relatively easy to phish, be it email, discord or WhatsApp.
I still wouldn't store "top-level secrets" in here and upload this to a cloud drive and forget about it. Someone smarter than me could spot a bug in your code (or the API's code) in a year and that renders your solution vulnerable. A browser's implementation of the API could be flawed in a particular version. Someone adversarial to me could bribe a number of people to get answers to 10 different password hints. There are some other scenarios that are implementation specific, I'm sure.
All in all, great tool. I hope you find more users if you are looking for more! :)
This also applies to most if not all challenges mentioned by other posters. Take phishing for example, at the moment all methods to exchange information of interest that are at the same time user friendly are relatively easy to phish, be it email, discord or WhatsApp.
I still wouldn't store "top-level secrets" in here and upload this to a cloud drive and forget about it. Someone smarter than me could spot a bug in your code (or the API's code) in a year and that renders your solution vulnerable. A browser's implementation of the API could be flawed in a particular version. Someone adversarial to me could bribe a number of people to get answers to 10 different password hints. There are some other scenarios that are implementation specific, I'm sure.
All in all, great tool. I hope you find more users if you are looking for more! :)