If you're using the *.3dsx version of sysUpdater, the Rosalina menu injected Homebrew Launcher (
boot.3dsx) should injected on
Homebrew Launcher Wrapper (*.cia version of HBL with HOME Menu icon).
You might have issues updating or downgrading system titles (ie, Health & Safety, AR Games, Download Play) if your HBL is injected in one of those while sysUpdater tries to modify it.
You may also elect to use the *.cia version of sysUpdater.
If that doesn't work, you can try downgrading to 11.5 by
CTRTransfer and then upgrading to 11.7 with sysUpdater.
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I'm not really sure what you're trying to accomplish by downgrading. You're not going to any safer staying on a lower firmware version. freeShop, CIAngel, and TIKdevil ??? are dead.
All future online gaming will require 11.8 if not already. You won't get banned using pirated games. Just don't cheat when you play.