Thank you for your reply. I tried the 'Verify Integrity of Game Files' on steam earlier this morning and it didn't solve it sadly. I noticed it saying about the missing file when I started looking closer at the SMAPI log again a few hours ago. I checked all the other logs I had that showed the same type of error for different events, as I'd saved them to a txt file to see if at some point I could work out what was wrong, and they all said they were missing a character file for that particular event, and yet when I went to the location it said it was missing from, there was always a file there!
The only difference I could see which I wondered if it would cause the error was that SMAPI said the missing file (in this instance) was the Jodi·.xnb file, whereas the file in the folder location says Jodi.xnb (without the "·" immediately after Jodi)! Would that cause that error, because all the other instances of apparent missing files were the same?
Anyway, for now I've found a solution that seems to be working! I just need to test a few more events to be sure! I removed the Event Repeater mod a couple of hours ago as I started wondering if maybe that was causing the 'event' errors I was having, and obviously also the mods which depended on it (which were all Xtardew mods), and so far all those errors seem to be gone (fingers crossed)! I can live without those mods if I have to. Maybe I'll try them again if they get a future update? For now though, as long as my game stays error free I'm happy.
Once again, thank you for your reply. I appreciate you taking the time to help. Hope you have a good day.