Off the top of my head: The only full-fledged planet left is Zheng Shi.
Also planets with relatively little content are Dhaal, Breedwell, Canadia, Poe A, Gastigoth.
Additionally, Uveto has a ton of presumed bugs need to be fixed, and I think some dungeons still haven't been ported (like KiroQuest, SaendraQuest, KaraQuest, Fall of the Phoenix, Princess Nastizia, etc)
Also,
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. I don't know what the fuck happened to it, but it's been teased since 2016. Possibly will be ported to Javascript version.