Yeah the commenting idea would be the easiest and fastest way to deal with it, but there's no easy way to review comment history so it might get tedious dealing with that if there are a lot of comments

If that's an issue, you could potentially give people a form that they can submit which will be prefilled to link to the Event in question, that way each comment is its own record and you can review it that way? 

The final (arguably overengineered) option is to create a form that has all of the same fields as the Event record and provide a prefilled link to that form for your users.  The user would then submit the form with whatever changes they want and you'd review that before creating a system to move the data over to the main table (probably an automation that copies the new values over or something).  This option's nice because you have an easily searchable change history for the events, but is way more work to set up than just using the second option

Thanks for that and taking the time to write such a great response!  I like the idea of the second option - but am I allowed to somehow put a form element on the same page as a record picker/list display? I think I’m struggling with how to make it easy for the user - when they see a line item they want to change, they can just easily submit a form within that view? Or is it a button that opens a form in a new window.

or - is this crazy, could I add a column for text that would just be to collect comments for that cycle of notes, that they could edit, but not any other fields?  

Ah I was thinking they'd click a button and it'd open a new window I'm afraid.  If they have Edit access, you can try giving them a linked field to another table?  And so their workflow would be: Click "Add record", the "+" and then fill out the form:

Hmm, yeah your idea is possible.  You'd have the same problem of it being difficult to review it though.  Also, if your plan doesn't have unlimited revision history, you'd eventually lose track of who wrote what, does that make sense?