Salam, yeah I saw that thread earlier! I was also going through the index on Project Root List (which I believe you created?) and it was listed under QRR. Both roots I mentioned seem to work, and early readings of the Quran show that grammarians have been disputing this for a long time.
I would translate it something like this: "And abide with dignity/content/uprightness in your homes, and do not make an excessive, extravagant display (of anything, wealth, beauty, greed)"--and 'tabarruj' here denotes conspicuous or provocative show-offy-ness.