Try with a fresh new copy of kosmos. It'll include a newer version of atmosphere. Make sure hekate is updated. Hekate is what will prevent your Switch from panicking since it has more burnt fuses than it should for that firmware. Follow the directions for kosmos. it'll tell you delete certain files. https://github.com/AtlasNX/Kosmos/releases
Now did you do this all on sysnand? Remember that you must use hekate to boot always if you downgraded sysnand. Horizon will freak it from having more fuses burnt than needed.
Once again I fell down the martial arts rabbit hole and am plumbing the murky depths of the internet's various martial arts and fighting crafts echo chambers.
If you're not actively involved and only get up to speed every few years or so, you can see the tide of public opinion flapping worse than my dong while I'm skipping naked down a hallway.