NCF – Extended list of Neutral creatures.

Ah, if the issue is specifically with IDs 190 and 191, then there's no problem at all in changing them to any other unused ID (and one that isn't marked on that forum) – it's not a problem at all. You just need to edit the text in 4 places, and that's it; it will work.

It's just that, at the moment, I personally have these slots free, which is why I chose them.

Well, the fact that they are free for someone is understandable, but you can't do it that way... because there are maps and scenarios in which the ranges of creatures are hardcoded in the scripts... and it can break the logic when playing through the map... for example, 190 is some kind of weak, low-level undead creature, and someone makes, for example, a 7th-level creature of flesh and blood under that ID... and if the creature that the map author intended to be spawned and reproduced under the number 190, then in the end some object or area of the map will become impassable!