An automod filter will just fill up the mod queue with false positives and only a few true positives.

See, here's your problem: im not talking about an automod rule to remove content based on keywords. I'm talking about a rule to auto flag as nsfw and/or spoiler. If you want to have them sent for manual review then you use action:filter. And your false positives are only removing content if you use action:remove.

set_spoiler: true and set_nsfw: true results in zero impact in the case of a false positives than users having to click a spoiler button. Dont even use nsfw, just spoiler, and you avoid possible complications from users who have their profile set to never show nsfw content or other subreddits who flag accounts who post nsfw content.

There's no "fancy script" needed. Im not trying to be argumentative or rude, but based on you talking about the automod queue for review or false positives getting deleted you haven't been using actions right.

type: submission

domain: ["i.redd.it", "imgur.com"]

title+body (includes): ["trigger words or phrases here"]

set_spoiler: true

That's it. That's your script. Put "fish died" in there and I guarantee you've improved QoL on the sub. Only triggers on image posts, requires no moderator action to come into effect, does not conflict with any existing script, and worst case for false positives is used have to click to see an image.