The starbounder wiki says the Glitch Castle can be found on any planet (which is true) but can found most often on volcanic worlds. Actually, it's found in grassland areas, similar to what you see on lush planets. On over twenty volcanic planets, only one had a Glitch Castle. The Glitch Evil Fortress and Glitch Dungeon Crawler was found in abundance, but the Glitch Castle, Glitch Village, and Old Sewers (which, I'm not sure, but I got the impression may be Glitch related?) are rarely found on the volcanic planets. I don't have an account on the wiki, as I'm not one to do much digging for information, but I just wanted to save someone else the headache of searching so many planets. I know the main quest says you can find the glitch there, but it must refer to those dungeons, or something. Grabbing the armed display armor was a giant pain because of this lol.
Where is your information coming from? The data says otherwise. https://i.imgur.com/UswwtWl.png ^Second to last row being "volcanic" planets in the terrestrial_worlds.config It is a weighted list, and while they do have a higher chance, there are still quite a few other options that decrease the odds against them. there are 23 options, and the 4 glitch themed dungeons have 3 extra chances each to be selected, so there is effectively a pool of 35, meaning that the glitch castle has a. 11.4% chance. Meaning there is an 88.6% chance of the dungeon NOT being a glitch castle.