We all do it. You can't deny it. When creating a world, new character, monster, place, building, monument, fort, castle, city, or whatever, the chances of making up a random word are very very high.

For example the two worlds in one of my original stories that I'm working on Enzarna and Korvunjar, or Moleck and Shadiya from ACBU (Assassin's Creed: Brothers Unite), or the Tongue of the Assassins (ACBU).

Everyone does it.

And nobody know how to correctly pronounce any of them... except the writer... who is always correcting the people who say them weird. :D