I know Brelyna's Practice is bugged that if you have spell absorption she'll cast her first spell, but it will never wear off and she'll repeat her dialogue about needing your help. However, USEP doesen't mention anything about Neloth's quests being bugged.

Well, only one way to find out. Perhaps you'll be the guy that posts the information on the uesp.

I'll just have to remember to save before starting the experiment quests.