I'm sure I read that 'chez lounge' is an acceptable alternative. Whether t'was always thus or that's because it's considered that so many people getting something wrong for long enough somehow makes it 'correct', I couldn't say.
Even said correctly, the name of the item of furniture just reminds me of that irritating song by Wet Leg which seems to have very few other words in the lyrics.
For me, I'd simply avoid it altogether and just go full-on Partridge: 'banquette' for me every single time!
I know it's not exactly the same thing, but it's a crying shame to waste the opportunity to use the word 'banquette' on any occasion when describing something roughly approximating to it 