The 'Von' that the people of Lichtell carry in their surnames means that they (or nowadays, their ancestors) seized, conquered or live near a certain place.
Their planet is seperated into multiple thousands of sections (kind of like countries), and each of them have names, like for example Cannes, which is a very wild but fruitful stretch of land that Maelle's ancestors conquered.
Since Maelle still has Von Cannes in her name, it means her family tree never moved from it and defended it against other folks. It's a symbol of power if your last name is still exactly like the name of your location, because it means your family managed to keep it safe over the years.
The Von Sales, Von Vos (Hank) and Von Reva (Easter and Annie) families wandered over the years, so their surnames changed.
Vos, Sales and Reva are broken down versions of the actual places. Their ancestors either traded or lost parts of their land.
Diamongal is more of a mishmash of names, meaning Dmitri's ancestors were often defeated by stronger families and thus had been forced to change their name.