Greasy Fork is available in English.
Hide system messages in your party on Habitica with this simple user style!
Only hides system messages on the party screen, which is the only place they're seen 99% of the time. (The other 1% being in the Tavern, during world bosses. I'm not comfortable implementing the style in a way that it would apply to that without immediately being able to test that kind of thing.)
User JS installation is disabled for this style because I have not implemented it outside of the party screen--this means the conversion Greasy Fork automatically does can work if installed as a user script, but only if the initial load of Habitica is onto the party screen (otherwise, it fails entirely). I may allow JS conversion/download if I remove the party page limitation.
Special thanks to Alys for posing the question that got me thinking about how to do it!