The biggest issue I have when designing adventures is the same one I have when designing characters as a player: naming them. I know what I want their skills, history and personality to be, because that all has a tangible effect, but a name can be anything. If it can be anything, how do I narrow down what it SHOULD be?
It gets even harder when designing adventures with multiple characters, all needing a name. I can't share names and have fifteen Jims, but I don't want to end up with the three human tavern owners Jim, Nunzio and Kxarbutlko. Different names that sound like they fit together... Very tricky, personally.
And I don't wanna just use foreign words, because I live in fear of the day when a Spaniard asks me why I named a villain "cabbage" or something. And it's surprisingly hard finding a relevant word that actually sounds like a decent name.
Sometimes the DM has to take clear and obvious shortcuts but just have fun with them.
Like in the "He who fights with monsters" books. Theres a bunch of largely unimportant recurring npc characters. So the author made them Octuplets. Albert, Bertram, Gilbert, Herbert, Philbert, Hubert, Robert, and Bertrand. The best thing about the brothers Bertinelli is that they all respond to "Bert".