When I was ambushed by ghouls I noticed that one of them paralyzed my ranger, which is a sylvan elf and therefore should be immune to it. Its a rare rule but ghouls attacks specifically state they only paralyze creatures that are neither undead nor elfs. Now I get if this was cut because the reason elfs are immune has something to do with the lore of ghouls and Solasta might have different lore for them, but just in case theres no lore reason this was cut and it was just overlooked, I wanted to mention it.
This behaved weirdly for me tonight - I just ran into a certain fairly tough undead fight while seeking the second gem (i.e. not Ashka, a bit later than that). One of the undead paralyzed my elf ranger, but she immediately became un-paralyzed again, before she could actually miss a turn from it. It wasn't a ghoul but one of the homebrew undead from this game, but those seem to be essentially ghouls with a few class abilities and a metric assload of extra hit points. Perhaps that was how they implemented the traditional elven immunity to ghoul paralysis?