MWEdit can't find it while parsing the dialogue... I'll have a look in TESCS; there are two warnings about strings being different.
Edit: OK, I'm using Comprehensive Chargen... it looks like the solution would be to move the Firemoth responses above the "Who are you? Where are your papers?" response during chargen...
I should've known using the original Siege at Firemoth's dialogue conditions would cause issues, like the rest of the original plug-in does.
I fixed the issue, I've placed the Firemoth-related greetings above the character generation greetings. This should fix the issue, as long as no other plug-in adds greetings to the same spot (don't think too many would). The expedition rumor will now trigger the Firemoth greetings, one can receive the rumor from any non-Dunmer NPC outside of Seyda Neen town limits, like in Pelagiad or Balmora. I'll get the fixed update posted later today. ^_^
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I've did some more work on the interiors, notably adding sounds and mist to the caverns and tomb for ambience. I've also started working on swapping all of the containers found in the interiors for Firemoth-specific containers, which'll give more flexibility with their contents.
Spoiler:
Spoiler Grurn can animate his guardians in the tomb, essentially giving Grurn an endless supply of guardians. However, the more times they are 'killed', the longer it takes to re-animate them. The only way to truely kill them is to kill Grurn.