That’s a nice idea re: red text to say that you’ve already reported the post and I’m pretty sure it’s easy to implement.
But I am against the reporting badges. For example, when my kids were young they would get stickers for doing good things, tidying up, etc. One evening I overheard them, they deliberately made a mess to then get a sticker for tidying up. Knowing human nature , I’m sure they would be plenty of people who would create alt accounts and deliberately produce spam to be able to report these posts, In order to get a “sticker”/badge !!
Sorry that’s my 2 sats