Sentry. It’s a dedicated error monitoring platform and I highly suggest you use it. If you have the GitHub student pack you can get 500K events/month (events are instances of data sent, be it an error or anything else), unlimited projects and members assigned to that project. I’d settle for no less unless there’s free options out there that have all the tooling I need.
Sentry does not have Lua support out-of-the-box, so you will need to follow a resource in order to get it running with your Roblox projects. There’s a tutorial for doing so that you can read up on:
Sheets isn’t adequate enough to log whole errors and messages externally but rather for minor projects and small pieces of data and Trello is inadequate in so many ways for this purpose including its slow speeds and the fact that it isn’t meant to be used as a logger or database.