If you are able to, during an upgrade, could you please add a prompt that makes you confirm that you are adding a favourite to your list?
For some reason, my fat fingers keep accidentally adding random characters to my favourite list, time and time again and one less rage-induced aneurism a day would probably work wonders.
Go to Roster > then look down the filters until you get to “favourites”.
You can sanity check you only have 3 favourites there at your leisure. (a 3, a 4 and a 5)
I’ve had a similar thing of doing a few pulls then going “wait, when did I favourite that random 4star?!?!”.
That’s the best workaround I can think of until they ever implement your suggestion
I also double check on the token info popup before I start doing my pulls for the day.