You can, but honestly you're just better off installing A9LH. It's about as much time and effort now than downgrading to 9.2.
And, strictly speaking, warranty is void the moment you run any unauthorised code, A9LH or not.
The good thing about 9.2 is you can simply take out the sd card, switch the homemenu theme and the 3DS is legit again. A9lh doesn't have this advantage so i'd rather have 9.2 than it.