The names you gave as examples are the key here. Both Hesperus and Phosphorus are single words and flow easily off the tongue. I suppose the North Star isn't, but the name also ties directly to it's important function.
By contrast, a tower of anything is not a description of the planet, it is a description of something on the planet. Imagine naming the "United States of America" "Wall Street" because that part of the country is the only part that the people who make the decisions care about. It wouldn't make sense, even if Wall Street was five times more important than it already is.
Now I'm not great at names myself, but if I was naming it it'd be something like "Little Abyss", or "Pandemonium's Palate," perhaps translated to Greek/Celtic.
The idea of the planet being alive and a single organism is an interesting idea and completely sidesteps my points about planet names, because at that point the inhabitants would view it not as a planet but as a weapon/organ which would shift their views including their naming conventions correspondingly. Curious.
Ohhh. You have a problem with the translations themselves being used as names, not the translation itself. Don't worry, Yrdarvyr, the main world for this game, means "Conflict" for Angels. I decided to release the solar system with the Literal translations of the planets names because I have yet to find a good sounding name for The Ministry of Truth and the Tower of Ashes. I could also easily explain why they are called that.
-Tower of Ashes was renamed like this after the succubus conquest of the planet. For succubus, they do not perceive planets like we do, but instead as "seats" or "towers" for their power. Since the planet is the closest to the sun creating a very barren and grey land, they renamed "Tower of Ashes". Succubus rename "Tower of ..." after their conquest.
-The Ministry of Truth is indeed considered a living entity by the Elves. The Elven government is ruled by Ministries (Defense, Spirit, Guidance, War, etc) using entire planets as headquarters for the specific Ministry. But never before have they created "Ministry of Truth". The elves wished to leave the Solar System, but many decided to stay and create a Ministry in that giant world you can see on the Solar System map. They created forests and fortified that world with magic, preparing for a possible invasion from hell. But what should they call their new Ministry? They choose the "Truth", out of arrogance, in showing that they will drive back anyone who dares invade their domain. Showing everyone (all the elves who left the system) that they were right in staying, they will show the "truth".
As you can see, I'm trying to give different perspectives to alien races about planets. As the generations progresses, humans will also give them names, probably saints or angels names (since the lore doesn't have actual gods).